bugGNU Octave - Bugs: bug #51580, isa: compatibility with isfloat,...


bug #51580: isa: compatibility with isfloat, isinteger and isnumeric

Submitted by:  Ernst Reissner <ernstreissner>
Submitted on:  Wed 26 Jul 2017 09:08:05 AM UTC  
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Matlab Compatibility
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  Open
Release:  dev Operating System:  Any

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Thu 27 Jul 2017 08:01:59 AM UTC, comment #2: 

Well, if you have a look at help isa,

then it turns out that for isa(x,"float"),
float is not really a class,
it is interpreted as 'floating point value'
comprising classes double and single.

So further classes may represent floats.

For classes double and single, the function isfloat(x)
returns true indicating that these are floats.
If I write my own class, then I would also define isfloat(x)
returning true.

Then isa(x,"float") can determine whether it is a float
just asking isfloat(x).

Ernst Reissner <ernstreissner>
Thu 27 Jul 2017 07:48:38 AM UTC, comment #1: 

I think that could be problematic in some cases. If isa (x, "float") returns true I expect that x actually is a standard Octave float. How would you in such a situation check if x is a standard float or a float of some other class?

Joel Dahne <urathai>
Wed 26 Jul 2017 09:08:05 AM UTC, original submission:  

I write an arithmetic with oo-means,
so overwriting isfloat, isinteger and isnumeric
for my own arithmetic classes.

In addition, i have to overwrite isa
for second argument 'float', 'integer' and 'numeric'.

I suggest to modify builtin function isa
so that for these second arguments
methods isfloat, isinteger and isnumeric are invoked.

This improves consistency and spares me overwriting function isa.

Ernst Reissner <ernstreissner>


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