Iterate through a list calling functions

[David Pratt]

Hi Kent.  Thank you for your reply.  I gave this a go but get the 
following traceback:
...
     result = validator(name, value)
TypeError: 'str' object is not callable

Have put validators in list and iterate over it as in following:

	validator_list = 
[isContainedIn,isDate,isDecimal,isEmail,isEmpty,isInteger...
  		more validators....]	
	results={}
	for validator in validators_list:
		result = validator(name, value)
		if type (result) in StringTypes:
			# do some stuff...
	return results

Regards,
David


On Sunday, June 5, 2005, at 02:03 PM, Kent Johnson wrote:

> David Pratt wrote:
>> Hi.  I am creating methods for form validation. Each validator has its
>> own method and there quite a number of these.  For each field, I want 
>> to
>> evaluate errors using one or more  validators so I want to execute the
>> appropriate validator methods from those available.  I am iterating 
>> over
>> each validator using validateField method to gather my results. It 
>> works
>> but it ugly and inefficient.  Can someone advise whether there is a
>> better way of doing this.  I realize that the validator variable in my
>> iteration is only a string so question is how can I make the validator
>> string reference a function so I may be able to shorten validateField 
>> to
>> something similar to this (instead of my long list of ifs which I am 
>> not
>> very happy with):
>>
>>     for validator in validators_list:
>>         result = validator(name, value)
>>         if type (result) in StringTypes:
>>         results[name] = result
>
> Actually you can do exactly that by putting references to the 
> validator functions in your list instead of (string) name. For example 
> if you have
> validators = [ 'isDecimal', 'isFoo', 'isBar' ]
>
> just change it to
> validators = [ isDecimal, isFoo, isBar ]
>
> and your loop above will work.
>
> Python makes data-driven programming easy :-)
> Kent
>
>>
>> Many thanks
>> David
>>
>> My current situation below:
>>
>> # A large list of validators
>> def isDecimal(name, value):
>>     """ Test whether numeric value is a decimal """
>>     result = validateRegex(name,
>>         value,
>>         r'^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$',
>>         errmsg='is not a decimal number.',
>>         ignore=None)
>>     return result
>>
>> def isZipCode(name, value):
>>     """ Tests if field value is a US Zip Code """
>>     result = validateRegex(name,
>>         value,
>>         r'^(\d{5}|\d{9})$',
>>         errmsg='is not a valid zip code.',
>>         ignore=None)
>>     return result
>>
>> ... more validators
>>
>> # Iterating over validators to gather field errors
>> def validateField(name, value, validators_list, range=None,
>> valid_values=None):
>>     """ Validates field input """
>>     results={}
>>     for validator in validators_list:
>>         if validator == 'isContainedIn':
>>             result = isContainedIn(name, value)
>>             if type (result) in StringTypes:
>>                 more...
>>         if validator == 'isDate':
>>             result = isDate(name, value)
>>             if type (result) in StringTypes:
>>                 more...
>>         if validator == 'isDecimal':
>>             result = isDecimal(name, value)
>>             if type (result) in StringTypes:
>>                 more...
>>
>>                  more validators ...
>>
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