`expr` behaves inconsistently when invoked directly vs with `=` (deprecated)

[tiymat]

Describe the bug: Invoking expr via expr gives different results than invoking it with = or just writing the expression.

Expected behaviour: Invoking an expression by any of the 3 possible ways should provide the same result.

Screenshots:

Platform (please complete the following information):

• OS, output from uname -a if supported: 6.9.7-arch1-1
• Terminal Emulator: kitty 0.35.2
• Murex version, output from version --no-app-name: 6.1.8300

Additional context Bracketing the expression seems to fix the issue as a workaround. e.g. expr (1 + 2) gives 3.

[lmorg]

The = syntax is old code where I relied on a 3rd party module to handle expressions. However because the syntax for = and expr differs slightly (where I was able to make improvements to Murex's parser to natively support expressions), it meant I was nervous about replacing = with the new code as it would cause braking changes. But the = code is now deprecated and will be removed in the next major release of Murex.

expr wasn't intended to be invoked manually because there's some special-case code handling parsing of expressions to make them more ergonomic, and that always doesn't translate well to statements. This is something I should update the docs to reflect.

That all said, the issue you ran into was definitely a bug because expr was only checking the first parameter. That's now fixed in develop

[tiymat]

Thanks for the fix! The specific part of the documentation that led to me trying it was the last example of the Usage block in the expr reference.

[lmorg]

@tiymat that's a very good point. Is the new docs (only in develop at the moment) any clearer? https://dev.murex.rocks/commands/expr.html#description

[tiymat]

@tiymat that's a very good point. Is the new docs (only in develop at the moment) any clearer? https://dev.murex.rocks/commands/expr.html#description

Definitely!