[Octave-bug-tracker] [bug #54698] Precedence of call/indexing operator over transpose operator

[anonymous]

Follow-up Comment #8, bug #54698 (project octave):

I have found the simplest solution!

Here is the first 3 rows of the current table of precedence
<https://octave.org/doc/v4.4.0/Operator-Precedence.html>:


    ‘()’ ‘{}’ ‘.’

    ‘++’ ‘--’       postfix increment/decrement

    ‘'’ ‘.'’ ‘^’ ‘**’ ‘.^’ ‘.**’
        ....


Other rows of the table are truncated because are unrelated to the current
discussion.

If all of them are assigned the same level of precedence the problem is
solved.
So all of them should be on the first row:


‘()’ ‘{}’ ‘.’ ‘++’ ‘--’ ‘'’ ‘.'’ ‘^’ ‘**’
‘.^’ ‘.**’


Now in the expression:


A.'.'.'(X)(Y)


Because the transpose operator and the call operator have the same level of
precedence the expression is executed from left to right.

Currently there is a bug about precedence of call/indexing operator over
postfix increment/decrement operator that now can be fixed as the current
issue.

Consider the expression:


a = [5 7];
b = a++(2);
disp(a)


Regarding the current table of precedence it should be evaluated as:


a = [5 7];
b = a(2);
a(2) = a(2) + 1;
disp(a)


But it is evaluated as:


a = [5 7];
b = a(2)
a = a + 1;
disp(a)


With the proposed modification to the documentation of the precedence table
this bug also can be resolved.

@Michael Leitner 
As you I think that "postfix increment and decrement group right to left." is
wrong and they group left to right.
Your second point about +++a is the same as c++ behavior. You can see this
stackoverflow question
<https://stackoverflow.com/questions/5236706/what-is-i-increment-in-c>. They
have noted that it is related to maximum munching rule.

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