Does the compiler do inlining?

Very rarely, because Perl is such a dynamic language, variables and even things such as subroutine declarations can change at any time and at a distance (kind of like volatile variables in C). The only place I can think of inlining off the top of my head is Constant Functions, the rest is optimization that Perl may or may not do internally (such as constant folding), but that should not be visible to the user.

But in general, it sounds to me like you might be drawing too many parallels between Perl and a truly compiled language such as C/C++, where there are things such as generating a binary and a very clear distinction between compile time and run time. In the Perl interpreter, the lines between the traditional "compile time" and "run time" can be blurred - you can run code at compile time with BEGIN and use, and compile and run code at runtime with eval, do, and require. "Compilation" is really just translating source code into the in-memory opcode tree, that the interpreter then executes (Update: remember that the perl binary is both the compiler and interpreter, which is why it can do the aforementioned flexible compile-/run-time things).

For example, here's a common mistake:

our $FOO = 1;
use if $FOO, 'SomeModule';
print $FOO, "\n";

[download]

This will compile fine and print 1, but SomeModule won't be loaded! What is going on here is that use is equivalent to a BEGIN block, which is code that will be executed during the compile time of the code. So our $FOO = 1; declares a variable $FOO, so that it can be used in the following use statement, but the assignment $FOO = 1 doesn't actually happen until runtime, at which time the use statement will have already finished executing. To fix this, one needs to write e.g. our $FOO; BEGIN { $FOO = 1 } to move the assignment into the compile time as well, before the use executes.

May I ask what the background of these questions is - is it just curiosity, or are you trying to implement something specific, or are having problems with something?

In reply to Re^3: What is an ordinary statement? by haukex
in thread What is an ordinary statement? by ntj

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


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.