Is there any writef() format specifier for a bool?

Question

I looked at the writef() documentation for any bool specifier and there didn't seem to be any.

In a Chapel program I have: ...

config const verify = false;
/* that works but I want to use writef() to also print a bunch of other stuff*/
writeln("verify = " + verify); 
writef("verify = %<what-specifier-goes-here>\n", verify);

This last statement works ok.

// I guess I could do:

writef( "verify = %s\n",if verify then "true" else "false");

Rundell

I thought that this was a reasonable feature request, so filed a GitHub issue against Chapel for it: chapel-lang.org/docs/latest/modules/standard/IO/… – Brien

Answer 1

Based on the FormattedIO documentation, there is not a bool specifier available in Chapel's formatted IO.

Instead, you can use the generic specifier (%t) to print bool types in formatted IO:

config const verify = false;
writef("verify = %t\n", verify);

This specifier utilizes the writeThis or readWriteThis method of the type to print the variable. The Chapel IO documentation provides more details on how these methods work.

Awesome

With all due respect Ben, what was any rational reason to roll back the improvement edits -- one corrected typo and added a more accurate explanation about the Chapel actually not having any writef(...)-formatting specifier for bool-eans, but having a possibility to use a smart-trick with a delegation of the FormattedIO presentation of a bool-hard-typed value ( brought in by the verify constant ) onto its own type-inherrited writeThis() routine? Any missed reason? Ref. >>> stackoverflow.com/revisions/47243896/2 – Goldi

Hey - sorry, I wish you could document rollbacks the same way you can document edits. I think the extra detail was good, but did not agree with the other minor edits. – Awesome

Not clear which exact part ( if any at all ) of the "minor edits" as you call it, have deserved your particular feeling that you cannot agree with their respective meaning so strong, that you have initiated a roll-back. Be rather specific and exact + argument why -- no exceptions, no excuse in this -- otherwise there still seems no rational reason for a roll-back. ( Btw -- as per your wish -- anyone can document calling a roll-back Ref. >>> stackoverflow.com/posts/47243896/revisions ) – Goldi

Apologies if I've broken SO etiquette by rolling back your edit. I've reincorporated the edits that I agreed with. Hopefully this is more clear. Thanks! – Awesome

Answer 2

No, there is no such <specifier> for bool in FormattedIO

As documentation explains, there is no such bool-value specific specifier in the recent Chapel language release.

A verify value-based conversion is fine.

config const verify    =  false;
var aTrueFalseAsSTRING = "false";

if verify then aTrueFalseAsSTRING = "true";

writef( "verify = %s\n",
         aTrueFalseAsSTRING
         );

Goldi