Beefy Boxes and Bandwidth Generously Provided by pair Networks
Problems? Is your data what you think it is?

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

From PL_keyword_plugin, an opcode tree must always be generated. Whatever code is generated, even a single no-op, perl should resume parsing the (possibly modified) code remaining in the source stream.

In the example in Keyword::Simple, the provided keyword was consumed by the parser and the keyword handler called. The handler "stuffed" if in front of the current content of the source stream, "generated" a no-op then returned KEYWORD_PLUGIN_STMT, leaving the rest of the statement for perl to finish parsing.

For a keyword in an expression, a similar series of steps should also work.

In the case of XS::APItest::KeywordRPN*, the handler would have had to parse the expression itself, consuming the expression. At that point, the handler could have either generated an op-code tree for the parsed expression, or stuffed the source stream with an equivalent expression that perl could parse and generated a no-op.

In theory, a no-op should no have effect (other than consuming time), even in the middle of an expression. When XS::APItest::KeywordRPN was working, it may be that it was generating an actual op-code tree for the RPN expression. In which case, that could be what's necessary to implement an "expression keyword". If it regenerated the expression for perl to parse, then probably something changed in the Plug-able Keyword API that XS::APItest::KeywordRPN was never updated to comply with.


* Other than downloading the source distribution for perl (which I have no inclination to do), I have not found the XS source for XS::APItest::KeywordRPN, so I can only theorize on how it worked.

In reply to Re^5: Devel::Declare is deprecated, what’s instead? (Keyword::Simple) by RonW
in thread Devel::Declare is deprecated, what’s instead? by dk

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (3)
As of 2023-02-03 19:41 GMT
Find Nodes?
    Voting Booth?
    I prefer not to run the latest version of Perl because:

    Results (29 votes). Check out past polls.