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The content of this blog is my personal opinion only. Although I am an employee - currently of Imagination Technologies's MIPS group, in the past of other companies such as Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

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Friday, June 29, 2012

Postfix if with else

Today I found myself writing

   do A if possible, else do B if possible, else error

English that is.

But it caused me to think about Perl's Postfix if

     statement if condition;
  versus
     if( condition ) {code} [[elsif(cond) {code}]* else {code}]
  i.e.

     if( condition ) {code}
     if( condition ) {code} else {code}
     if( condition ) {code} elsif(cond) {code} else {code}
   etc.

Strange to many programming languages, but sometimes makes conde more readable.

I wonder if the posifix if woth else, that I wrote in English, might be worth thinking about.

Syntactically  it is a ternary operator:
      operand1  IF operand2 ELSE operand3

I vaguely recall disjoint operator and function syntax - Algol 68? or was it Algol 60? - ...





1 comment:

Unknown said...

VHDL can do this:

some_signal <= some_value when some_condition_is_true else some_other_value;

and even

some_signal <=
some_value when some_condition_is_true else
some_other_value when some_other_condition_is_true else
some_default_value;