[GAP Forum] function search feature

[kroeker]

update:

replace
"obj:=5; for each filter in FILTERS do filter(obj); od;"
with
"obj:=5; for filter in FILTERS do filter(obj); od;"

Am 25.02.2012 00:02, schrieb kroeker:
> Hello Frank,
>
>
> thanks, "AllOperations" comes already very close to my needs.
> Maybe you could also give me an advice, how to find
> all filters which are applicable to an object:
>
> "IsEmpty" is not applicable to an int and therefore
> "obj:=5; for each filter in FILTERS do filter(obj); od;"
> fails with an error.
>
>
> Thank you,
>
>
>
> Jakob
>
>
> Am 23.02.2012 23:07, schrieb Frank Lübeck:
>> On Thu, Feb 23, 2012 at 08:11:20PM +0000, Alexander Konovalov wrote:
>>> I've noticed that this question was not answered yet in the Forum:
>>>
>>> On 9 Jan 2012, at 09:59, kroeker wrote:
>>>
>>>> Hello,
>>>>
>>>> sometimes I am looking for a function which is applicable to a 
>>>> specific object
>>>> without knowing the name of the function. To find the desired function
>>>> I have to read a lot of documentation, look for examples, ask an 
>>>> experienced GAP programmer (or the GAP-Forum) and so on.
>>>>
>>>> Would it be possible to implement a search through all existing 
>>>> functions
>>>> where one of the parameters is an object of a specified type?
>>> So, the short answer is 'No' - GAP function may take any 
>>> argument(s), one does not
>>> specify to which arguments it applies when the function is created. 
>>> GAP also
>>> has a notion of 'operation' which is a bunch of functions, called 
>>> 'methods'
>>> - these are installed with particular requirements on their 
>>> arguments. Here
>>> you may call ApplicableMethod (see ?ApplicableMethod) to get the 
>>> function
>>> which will be applied to arguments in a call to a specified 
>>> operation - but
>>> this is not what you want, since you need to know the name of the 
>>> operation
>>> in advance. For example,
>> Dear Jakob, dear Forum,
>>
>> Sorry, I must have overlooked the original post.
>>
>> This reminds me that I have once written a utility function
>>     AllOperations(obj)
>> which returns a list of 6 lists of names of operations such that
>> the operations from the i-th list have a method that allows obj as
>> argument number i.
>>
>> I think (a variant of) this is used for a completion function in the
>> Sage interface to GAP. The function is appended below.
>>
>> As Alexander pointed out, something like that is only possible for
>> operations (whose methods are installed with requirements on the 
>> arguments)
>> and not for general functions in GAP.
>>
>> With best regards,
>>    Frank
>>
>
>
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