Can't get operator to work.

[Vernon Brown]

I created a simple Integer formatting function that let's you right align an integer image in a string with a specified width.

It's defined as:

  func Format(Format_Str : Univ_String; Value : Univ_Integer) -> Univ_String

An example call to Format is:

  var y := "3d".Format(x)

The above works just fine, but seems a little "wordy".

So, in the spirit of the ` operator, I tried to replace Format with "+" using the declaration:

  op "+"(Format_Str : Univ_String; Value : Univ_Integer) -> Univ_String is Format;

But, I can't get this operator to work at all.

I tried:

  y := "3d"+x;

  y := "3d"."+"(x);

  y := "+"("3d",x);

  y := Univ_String::"+"("3d",x);

none of which worked.

I get errors similar to:

  Error: use of op "+" not resolved:

  Info:   "3d" + x

  Info: operand's type Univ_String<> does not match param type Univ_Integer<>

  Info: operand "3d" does not match Left : Univ_Integer

  Error: Cannot resolve type:

What am I doing wrong?

I attached a working example with the non-working lines commented out.

[Tucker Taft]

Operator visibility is special.  Operators are only visible if they are defined where a type is defined and they have a parameter or result of the type.  So you would have to define a new type, e.g. a Format_String, and then you could define an operator that operated on it.  But even then you would still have a challenge, since you want a string literal like "3d" to be interpreted as a Format_String when "appropriate" and the ParaSail parser has a rough time doing that.

I have attached a version of Format.psl that works, but I had to help it by declaring a local Format_String "F" initialized from "3d" which doesn't really seem to achieve the conciseness you were hoping for.

What you might do is define a function with a shorter name, such as simply "f", as a rename of "Format" and then generally write:

      f("3d", x)

or

     "3d".f(x)

which is pretty economical in terms of characters.

Take care,

-Tuck

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