Talk:Runtime evaluation/In an environment

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Why marked as incorrect?

This task needs to be clarified. The first part says something, that seems almost clear and generic. The points make it obscure, or better, they make the task redundant, since we are in the domain of first-class function, lambda calculus, or block closures; all treated already elsewhere (and the name "eval in environment" seems misleading). It is also unclear why Perl is not marked, while PHP is... they seem the same (and also Tcl).

  • it means it must look like code, not inside a string...: block closure (à-la Smalltalk), or just "lambda" calculus if you prefer the name. (Python contains a string, so it is wrong too) ??
  • x must be a dummy name... again: block closure or similar ??
  • "x" (dummy var) is local (inside the "block"); of course... ??

What about? --ShinTakezou 00:06, 30 April 2009 (UTC)

The first point means that you're not supposed to write e.g. (in JavaScript) eval("function (x) { return " + providedSourceCode + "}") (unless there is no other way). It does *not* mean that the parameter should be a block/closure/function object; the reason I didn't write "string" is to allow for parsed-but-not-evaluated code objects such as exists in E and Lisp.

x should not be global in the sense that the values given to it are visible to code other than the code being evaluated. In the Perl example, the variable is made local (lexical) by my; in the PHP example I (perhaps mistakenly) assumed that an undeclared variable is global. If that is wrong, please delete the flag on the PHP example. --Kevin Reid 02:01, 30 April 2009 (UTC)

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