[GAP Forum] "IsRationalNumber" as synonym for "IsRat"

[Alexander Konovalov]

Dear Jakob,

On 23 Feb 2012, at 13:55, kroeker wrote:

> Dear Alexander, dear GAP forum,
> 
> 
> it is ok to have short names but also consider that in software engineering  it is known
> that variable and function names should  be as descriptive as possible
> (and at the same time not too long of course).

In this case then 'IsPosRat' is certainly more descriptive than 'IsPR',
and, moreover, it naturally follows GAP naming conventions for some
central categories of objects. 

> My intention is not to customize my personal use but to improve the usability and code readability for everybody.
> So I can't see any serious arguments against introducing the synonym "IsRationalNumber" for now.

There is a guidance in the GAP manual about using synonyms, which says:

----
Two typical intended usages are to declare an "and-filter", e.g.

DeclareSynonym( "IsGroup", IsMagmaWithInverses and IsAssociative );

and to provide a previously declared global function with an alternative name, e.g.

DeclareGlobalFunction( "SizeOfSomething" );
DeclareSynonym( "OrderOfSomething", SizeOfSomething );

Note: Before using DeclareSynonym in the way of this second example, one should 
determine whether the synonym is really needed. Perhaps an extra index entry in 
the documentation would be sufficient.
----

From this, I don't think that there are any serious arguments in favour of the 
synonym IsRationalNumber for IsRat. It's really easy to find the meaning of 
IsRat using the help system, and if one searches for rationals in the 
documentation, then IsRat comes in the next manual section. You may grep the 
GAP library code to see actual examples when it is used in the library - in 
most cases there are much more grounds to introduce synonyms there.

Best,
Alexander

> Am 22.02.2012 23:13, schrieb Alexander Konovalov:
>> Dear Jakob, dear GAP Forum,
>> 
>> On 21 Feb 2012, at 19:04, kroeker wrote:
>> 
>>> Dear GAP-developers,
>>> 
>>> I do not really like the function name  "IsRat" for the check if an object is a rational number
>>> and suggest to introduce the synonym "IsRationalNumber" :
>>>  DeclareSynonym("IsRationalNumber",IsRat);
>>> 
>>> What is your opinion?
>>> 
>>> Jakob
>> GAP as a number of short names for such common categories like e.g. `IsInt', `IsPosInt', `IsCyc',
>> `IsBool', `IsFFE', `IsChar', `IsPerm' etc., so to my mind `IsRat' fits this naming scheme quite
>> well. These are used in many method installations and having compact names is quite handy.
>> 
>> The page http://www.gap-system.org/Faq/Usage/usage1.html explains how to customise GAP using the
>> .gaprc file, so if you prefer this synonym for your personal use, you may add this line there.
>> Of course, any code using it will not work without this declaration.
>> 
>> Best wishes,
>> Alexander
> 
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--
Dr. Alexander Konovalov               School of Computer Science
& Centre for Interdisciplinary Research in Computational Algebra
University of St Andrews                 Tel +44/0 (1334) 461633
http://www.cs.st-andrews.ac.uk/~alexk    Fax +44/0 (1334) 463278
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