Programming Forums > Script Programming > Python

Sane · Jul 11th, 2006, 7:50 PM

Was there something wrong with mine?

Just do some simple modifications on it to suit your needs. It should work fine. I don't see why not?

titaniumdecoy · Jul 11th, 2006, 8:21 PM

I need to be able to store and read tuples, so TUPLE=one,two,three corresponds to ('one', 'two', 'three'). However, I may use your code after making this and other modifications, if I can't get ConfigParser to work.

Also, no one answered one of my previous questions--Is it possible to somehow extract the names of the variables in the ConfigParser file?

Sane · Jul 11th, 2006, 8:37 PM

Does this help?

(Toggle Plain Text)

def cut_space(item):
    for char in range(len(item)):
        if item[char] != ' ':
            value = item[char:]
            break
    return value

def str_reverse(item):
    value = ''
    for char in item:
        value = char+value
    return value
                
class conf:
    def __init__(self, filename):
        self.CONF_FILE = filename

    def save(self, opts):

        data = []
        for key in opts:
            
            value = opts[key]

            typekey = type(value)
            if typekey == tuple or typekey == list:
                value = ', '.join([str(item) for item in value])
                
            data.append('%s = %s'%(key, value))
                    
        stream = open(self.CONF_FILE, 'w')
        stream.write('\n'.join(data))
        stream.close()

    def load(self):

        stream = open(self.CONF_FILE, 'r')
        data = stream.read().split('\n') # readlines keeps the \n there, I don't like that
        stream.close()

        opts = dict()

        for line in data:
            newline = line.split('=', 1)

            if len(newline) < 2:
                raise Exception, 'A line without an equal sign was found'

            key = str_reverse(newline[0])
            key = cut_space(key) # we are cutting space backwards, since the equal sign is on the right
            key = str_reverse(key)

            values = newline[1].split(',')

            newvalues = list()
            for value in values:
                newvalue = cut_space(value)

                try:
                    newvalue = int(newvalue)
                except ValueError: pass

                newvalues += [newvalue]

            if len(newvalues) > 1:
                opts[key] = tuple(newvalues)
            else:
                opts[key] = newvalues[0]

        return opts
                

if __name__ == '__main__':
            
    data = conf('options.conf')

    data.save( {'level' : 4,
                'volume' : 9,
                'graphics' : 'high',
                'event' : 4112,
                'position' : (123, 134),
                'names' : 'saney, titaniumdeocy,arevos, Cerulean',
                'list' : ['accept', 'my list', 'as well']} )

    options = data.load()

    print options['graphics']
    print options['position']
    print options['list']

def cut_space(item):
    for char in range(len(item)):
        if item[char] != ' ':
            value = item[char:]
            break
    return value

def str_reverse(item):
    value = ''
    for char in item:
        value = char+value
    return value
                
class conf:
    def __init__(self, filename):
        self.CONF_FILE = filename

    def save(self, opts):

        data = []
        for key in opts:
            
            value = opts[key]

            typekey = type(value)
            if typekey == tuple or typekey == list:
                value = ', '.join([str(item) for item in value])
                
            data.append('%s = %s'%(key, value))
                    
        stream = open(self.CONF_FILE, 'w')
        stream.write('\n'.join(data))
        stream.close()

    def load(self):

        stream = open(self.CONF_FILE, 'r')
        data = stream.read().split('\n') # readlines keeps the \n there, I don't like that
        stream.close()

        opts = dict()

        for line in data:
            newline = line.split('=', 1)

            if len(newline) < 2:
                raise Exception, 'A line without an equal sign was found'

            key = str_reverse(newline[0])
            key = cut_space(key) # we are cutting space backwards, since the equal sign is on the right
            key = str_reverse(key)

            values = newline[1].split(',')

            newvalues = list()
            for value in values:
                newvalue = cut_space(value)

                try:
                    newvalue = int(newvalue)
                except ValueError: pass

                newvalues += [newvalue]

            if len(newvalues) > 1:
                opts[key] = tuple(newvalues)
            else:
                opts[key] = newvalues[0]

        return opts
                

if __name__ == '__main__':
            
    data = conf('options.conf')

    data.save( {'level' : 4,
                'volume' : 9,
                'graphics' : 'high',
                'event' : 4112,
                'position' : (123, 134),
                'names' : 'saney, titaniumdeocy,arevos, Cerulean',
                'list' : ['accept', 'my list', 'as well']} )

    options = data.load()

    print options['graphics']
    print options['position']
    print options['list']

titaniumdecoy · Jul 11th, 2006, 11:38 PM

Thanks, Sane. That looks good. I'll try it out and tell you how it goes.

EDIT: *Mr. Burns voice* Excellent...

titaniumdecoy · Jul 12th, 2006, 12:36 AM

@Sane: I made some minor changes to your code. I couldn't figure out the purpose of the cut_space or str_reverse functions so I got rid of them--FYI, neither the keys nor values should contain spaces. I also simplified the rest as much as I could. In case you're interested (it's your code, after all), I posted the result below. It works great, although it's too bad it has to rewrite the entire file every time it's saved.

(Toggle Plain Text)

def forcetype(string):
    if '.' in string:
        try: return float(string)
        except ValueError: pass
        
    try: return int(string)
    except ValueError: pass
    
    return string

class Conf:
    def __init__(self, filename):
        self.CONF_FILE = filename

    def save(self, opts):
    
        data = []
        for key in opts:
            value = opts[key]

            if type(value) in (tuple, list):
                value = ', '.join([str(item) for item in value])
            
            data.append('%s = %s'%(key, value))

        stream = open(self.CONF_FILE, 'w')
        stream.write('\n'.join(data))
        stream.close()

    def load(self):

        stream = open(self.CONF_FILE, 'r')
        data = stream.read().split('\n')
        stream.close()

        opts = dict()

        for line in data:
            newline = line.split('=', 1)
            
            key = newline[0].strip()
            values = [forcetype(v.strip()) for v in newline[1].split(',')]

            opts[key] = len(values) > 1 and tuple(values) or values[0]

        return opts

DaWei · Jul 12th, 2006, 6:37 AM

Any time you modify a file (rather than merely append), you generally wind up rewriting the whole thing. There are ways to get around it but the effort, if you aren't working at a low level (knowledge and access at the file-system level or drive level) is rarely worth it. There's certainly no performance benefit and the resource benefits range from zilch to niggling.

Sane · Jul 12th, 2006, 7:33 AM

There were purposes for the cut_space and str_reverse functions. If you read one of the comments in the code, it said...

(Toggle Plain Text)

# we are cutting space backwards, since the equal sign is on the right

Which is why we need to reverse the string first. To cut space from right to left.

And we need to cut the space, to handle several different possibilities for how the user could have changed the file.

(Toggle Plain Text)

position1 = x, y
position2 = x,y
position3= x, y
position4= x,y
position5 =x, y
position6 =x,y
position7=x, y
position8=x,y

The code needs to be able to handle any of those 8 basic variations. As well as any extentions upon them as well (EG, two spaces). Then it needs to produce the exact same result. When you allow the user to have manual control of data files, you've put your data at the risk of the user's lack of perfection.

To make things short, my code does that, yours does not.

Just try copy pasting that in to your configuration file, and see if position1-8 all output the same thing.

And one more thing, I see you took out the exception handling. Even though it will be caught on this line...

(Toggle Plain Text)

values = [forcetype(v.strip()) for v in newline[1].split(',')]

... it is still generally, a good idea, to catch errors and raise exceptions when they happen. Instead of just waiting for their dependant code to crash.

titaniumdecoy · Jul 12th, 2006, 1:33 PM

@Sane: What's the difference between "cutting spaces" from each side and simply calling the strip function (or lsrip/rstrip), which is what my code does? The output from pasting that snippet into my configuration file is the same as yours:

(Toggle Plain Text)

>>> for key in options: print key, options[key]
position8 ('x', 'y')
position2 ('x', 'y')
position3 ('x', 'y')
position1 ('x', 'y')
position6 ('x', 'y')
position7 ('x', 'y')
position4 ('x', 'y')
position5 ('x', 'y')

Sane · Jul 12th, 2006, 1:48 PM

Oh wow... I actually had no clue at all that ' asd '.strip() would output 'asd'.

Learned something new.

titaniumdecoy · Jul 12th, 2006, 2:04 PM

Hmph. I just noticed that Python dicts save their contents in what appears to be pseudo-random order:

(Toggle Plain Text)

>>> print { 'd': 4, 'a': 1, 'b': 2, 'c': 3 }
{'a': 1, 'c': 3, 'b': 2, 'd': 4}

Is there any way to tell a dict to preserve the order of its contents according to the order in which they are added?

I somehow need to preserve the order of variables stored in the configuration file, along with the relative position of comments.

Jul 11th, 2006, 8:37 PM	#13
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	Does this help? (Toggle Plain Text) def cut_space(item): for char in range(len(item)): if item[char] != ' ': value = item[char:] break return value def str_reverse(item): value = '' for char in item: value = char+value return value class conf: def __init__(self, filename): self.CONF_FILE = filename def save(self, opts): data = [] for key in opts: value = opts[key] typekey = type(value) if typekey == tuple or typekey == list: value = ', '.join([str(item) for item in value]) data.append('%s = %s'%(key, value)) stream = open(self.CONF_FILE, 'w') stream.write('\n'.join(data)) stream.close() def load(self): stream = open(self.CONF_FILE, 'r') data = stream.read().split('\n') # readlines keeps the \n there, I don't like that stream.close() opts = dict() for line in data: newline = line.split('=', 1) if len(newline) < 2: raise Exception, 'A line without an equal sign was found' key = str_reverse(newline[0]) key = cut_space(key) # we are cutting space backwards, since the equal sign is on the right key = str_reverse(key) values = newline[1].split(',') newvalues = list() for value in values: newvalue = cut_space(value) try: newvalue = int(newvalue) except ValueError: pass newvalues += [newvalue] if len(newvalues) > 1: opts[key] = tuple(newvalues) else: opts[key] = newvalues[0] return opts if __name__ == '__main__': data = conf('options.conf') data.save( {'level' : 4, 'volume' : 9, 'graphics' : 'high', 'event' : 4112, 'position' : (123, 134), 'names' : 'saney, titaniumdeocy,arevos, Cerulean', 'list' : ['accept', 'my list', 'as well']} ) options = data.load() print options['graphics'] print options['position'] print options['list'] def cut_space(item): for char in range(len(item)): if item[char] != ' ': value = item[char:] break return value def str_reverse(item): value = '' for char in item: value = char+value return value class conf: def __init__(self, filename): self.CONF_FILE = filename def save(self, opts): data = [] for key in opts: value = opts[key] typekey = type(value) if typekey == tuple or typekey == list: value = ', '.join([str(item) for item in value]) data.append('%s = %s'%(key, value)) stream = open(self.CONF_FILE, 'w') stream.write('\n'.join(data)) stream.close() def load(self): stream = open(self.CONF_FILE, 'r') data = stream.read().split('\n') # readlines keeps the \n there, I don't like that stream.close() opts = dict() for line in data: newline = line.split('=', 1) if len(newline) < 2: raise Exception, 'A line without an equal sign was found' key = str_reverse(newline[0]) key = cut_space(key) # we are cutting space backwards, since the equal sign is on the right key = str_reverse(key) values = newline[1].split(',') newvalues = list() for value in values: newvalue = cut_space(value) try: newvalue = int(newvalue) except ValueError: pass newvalues += [newvalue] if len(newvalues) > 1: opts[key] = tuple(newvalues) else: opts[key] = newvalues[0] return opts if __name__ == '__main__': data = conf('options.conf') data.save( {'level' : 4, 'volume' : 9, 'graphics' : 'high', 'event' : 4112, 'position' : (123, 134), 'names' : 'saney, titaniumdeocy,arevos, Cerulean', 'list' : ['accept', 'my list', 'as well']} ) options = data.load() print options['graphics'] print options['position'] print options['list'] Last edited by Sane; Jul 11th, 2006 at 8:51 PM.

Jul 11th, 2006, 11:38 PM	#14
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Thanks, Sane. That looks good. I'll try it out and tell you how it goes. EDIT: Mr. Burns voice Excellent... Last edited by titaniumdecoy; Jul 11th, 2006 at 11:50 PM.

Jul 12th, 2006, 12:36 AM	#15
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	@Sane: I made some minor changes to your code. I couldn't figure out the purpose of the cut_space or str_reverse functions so I got rid of them--FYI, neither the keys nor values should contain spaces. I also simplified the rest as much as I could. In case you're interested (it's your code, after all), I posted the result below. It works great, although it's too bad it has to rewrite the entire file every time it's saved. (Toggle Plain Text) def forcetype(string): if '.' in string: try: return float(string) except ValueError: pass try: return int(string) except ValueError: pass return string class Conf: def __init__(self, filename): self.CONF_FILE = filename def save(self, opts): data = [] for key in opts: value = opts[key] if type(value) in (tuple, list): value = ', '.join([str(item) for item in value]) data.append('%s = %s'%(key, value)) stream = open(self.CONF_FILE, 'w') stream.write('\n'.join(data)) stream.close() def load(self): stream = open(self.CONF_FILE, 'r') data = stream.read().split('\n') stream.close() opts = dict() for line in data: newline = line.split('=', 1) key = newline[0].strip() values = [forcetype(v.strip()) for v in newline[1].split(',')] opts[key] = len(values) > 1 and tuple(values) or values[0] return opts def forcetype(string): if '.' in string: try: return float(string) except ValueError: pass try: return int(string) except ValueError: pass return string class Conf: def __init__(self, filename): self.CONF_FILE = filename def save(self, opts): data = [] for key in opts: value = opts[key] if type(value) in (tuple, list): value = ', '.join([str(item) for item in value]) data.append('%s = %s'%(key, value)) stream = open(self.CONF_FILE, 'w') stream.write('\n'.join(data)) stream.close() def load(self): stream = open(self.CONF_FILE, 'r') data = stream.read().split('\n') stream.close() opts = dict() for line in data: newline = line.split('=', 1) key = newline[0].strip() values = [forcetype(v.strip()) for v in newline[1].split(',')] opts[key] = len(values) > 1 and tuple(values) or values[0] return opts

Jul 12th, 2006, 6:37 AM	#16
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Any time you modify a file (rather than merely append), you generally wind up rewriting the whole thing. There are ways to get around it but the effort, if you aren't working at a low level (knowledge and access at the file-system level or drive level) is rarely worth it. There's certainly no performance benefit and the resource benefits range from zilch to niggling. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jul 12th, 2006, 7:33 AM	#17
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	There were purposes for the cut_space and str_reverse functions. If you read one of the comments in the code, it said... (Toggle Plain Text) # we are cutting space backwards, since the equal sign is on the right # we are cutting space backwards, since the equal sign is on the right Which is why we need to reverse the string first. To cut space from right to left. And we need to cut the space, to handle several different possibilities for how the user could have changed the file. (Toggle Plain Text) position1 = x, y position2 = x,y position3= x, y position4= x,y position5 =x, y position6 =x,y position7=x, y position8=x,y position1 = x, y position2 = x,y position3= x, y position4= x,y position5 =x, y position6 =x,y position7=x, y position8=x,y The code needs to be able to handle any of those 8 basic variations. As well as any extentions upon them as well (EG, two spaces). Then it needs to produce the exact same result. When you allow the user to have manual control of data files, you've put your data at the risk of the user's lack of perfection. To make things short, my code does that, yours does not. Just try copy pasting that in to your configuration file, and see if position1-8 all output the same thing. And one more thing, I see you took out the exception handling. Even though it will be caught on this line... (Toggle Plain Text) values = [forcetype(v.strip()) for v in newline[1].split(',')] values = [forcetype(v.strip()) for v in newline[1].split(',')] ... it is still generally, a good idea, to catch errors and raise exceptions when they happen. Instead of just waiting for their dependant code to crash.

Jul 11th, 2006, 7:50 PM	#11
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	Was there something wrong with mine? Just do some simple modifications on it to suit your needs. It should work fine. I don't see why not?

Jul 11th, 2006, 8:21 PM	#12
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	I need to be able to store and read tuples, so TUPLE=one,two,three corresponds to ('one', 'two', 'three'). However, I may use your code after making this and other modifications, if I can't get ConfigParser to work. Also, no one answered one of my previous questions--Is it possible to somehow extract the names of the variables in the ConfigParser file?

Jul 12th, 2006, 1:33 PM	#18
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	@Sane: What's the difference between "cutting spaces" from each side and simply calling the strip function (or lsrip/rstrip), which is what my code does? The output from pasting that snippet into my configuration file is the same as yours: (Toggle Plain Text) >>> for key in options: print key, options[key] position8 ('x', 'y') position2 ('x', 'y') position3 ('x', 'y') position1 ('x', 'y') position6 ('x', 'y') position7 ('x', 'y') position4 ('x', 'y') position5 ('x', 'y') >>> for key in options: print key, options[key] position8 ('x', 'y') position2 ('x', 'y') position3 ('x', 'y') position1 ('x', 'y') position6 ('x', 'y') position7 ('x', 'y') position4 ('x', 'y') position5 ('x', 'y')

Jul 12th, 2006, 1:48 PM	#19
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	Oh wow... I actually had no clue at all that ' asd '.strip() would output 'asd'. Learned something new.

Jul 12th, 2006, 2:04 PM	#20
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	Hmph. I just noticed that Python dicts save their contents in what appears to be pseudo-random order: (Toggle Plain Text) >>> print { 'd': 4, 'a': 1, 'b': 2, 'c': 3 } {'a': 1, 'c': 3, 'b': 2, 'd': 4} >>> print { 'd': 4, 'a': 1, 'b': 2, 'c': 3 } {'a': 1, 'c': 3, 'b': 2, 'd': 4} Is there any way to tell a dict to preserve the order of its contents according to the order in which they are added? I somehow need to preserve the order of variables stored in the configuration file, along with the relative position of comments.

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