Are PHP libraries linked dynamically or statically?

[Martin Larsen]

Hi,

When a PHP program links to a library using include or require (or their
_once variations), is the library then linked dynamically or statically?

While it might seem irrelevant from a technical point of view, the
linking method is important when it comes to licencing issues as some
licences, like GPL, differ between those kinds of linking when it comes
to viewing the library as a derivative work of the main program.

Therefore it is quite important to know what kind of linking is in
effect when including libraries, and I hope someone in this group can
shed some light on this matter.

Thank you very much in advance,
Martin

[NC]

On Jul 19, 4:14 pm, Martin Larsen <martin+spamfre e+lar...@bigfoo t.com>
wrote:

>
When a PHP program links to a library using include
or require (or their _once variations), is the library
then linked dynamically or statically?

Neither. include/require is not a linking mechanism; it is a way to
assemble a complete block of source code prior to its interpretation.
Any static linking takes place at the server process start-up (i.e.,
before any include/require can happen); dynamic linking (if any)
occurs during execution (i.e., after the source code has been
interpreted, and, therefore, after any include/require).

it is quite important to know what kind of linking is in
effect when including libraries,

Only if the libraries are true libraries (i.e., those compiled into
native executable code). With PHP "libraries" , using include/require
does not imply any linking...

Cheers,
NC

[Toby A Inkster]

Martin Larsen wrote:

When a PHP program links to a library using include or require (or their
_once variations), is the library then linked dynamically or statically?

Dynamically.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 29 days, 14:30.]

Parsing an HTML Table with PEAR's XML_HTTPSax3
http://tobyinkster.co.uk/blog/2007/0...table-parsing/

[Martin Larsen]

Thanks NC,

I understand that PHP is very different than say a Windows executable,
and perhaps linking is not the right term for what happens.

Anyway, in your opinion, does the mechanism rememble dynamic or static
linking most?

Btw, if I were to get an "official" statement, do you by chance know who
I should contact?

Martin

[NC]

On Jul 20, 12:34 pm, Jerry Stuckle <jstuck...@attg lobal.netwrote:

>

I understand that PHP is very different than say a Windows
executable,

PHP isn't (it can be a Windows executable). PHP scripts are.

Not quite true. The PHP interpreter (php.exe) itself is executable.

My point exactly. I guess I should have written "PHP interpreter"
rather than just "PHP"... :)

Cheers,
NC

[Martin Larsen]

NC wrote:

>Btw, if I were to get an "official" statement, do you by
chance know who I should contact?

The PHP group: http://www.php.net/contact.php

Thanks for link. However, that page actually refers to this newsgroup or
the webmaster for website related comments.

Is there a way to contact the PHP Group directly?

Thanks again,
Martin

[Martin Larsen]

Hi Henk,

This may be true from a strict technical definition, but juridical
reasoning may not be that strict.

Thank you for making clear what I was trying to say. It is in fact a
juridical matter.

If we agree that the term linking might not be entirely irrelevant,
which kind of linking would you say is in effect when a PHP program
links to a script: dynamically or statically.

The reason why this is important is that dynamically linking is often
seen as a licence boundary
(http://en.wikipedia.org/wiki/Library...ynamic_linking)

Regards,
Martin

[Jerry Stuckle]

Martin Larsen wrote:

Hi Henk,

>This may be true from a strict technical definition, but juridical
reasoning may not be that strict.

Thank you for making clear what I was trying to say. It is in fact a
juridical matter.

If we agree that the term linking might not be entirely irrelevant,
which kind of linking would you say is in effect when a PHP program
links to a script: dynamically or statically.

The reason why this is important is that dynamically linking is often
seen as a licence boundary
(http://en.wikipedia.org/wiki/Library...ynamic_linking)

Regards,
Martin

And despite what Henk posted, has absolutely nothing to do with PHP.

NC is correct in his discussion. You need to paying attention to what
he is saying.
--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Jerry Stuckle]

Martin Larsen wrote:

NC wrote:

>>Btw, if I were to get an "official" statement, do you by
chance know who I should contact?

The PHP group: http://www.php.net/contact.php

Thanks for link. However, that page actually refers to this newsgroup or
the webmaster for website related comments.

Is there a way to contact the PHP Group directly?

Thanks again,
Martin

Why?

If you understood the technology, the answer would be clear. Rather, I
suggest you visit your local library or bookstore and find out how
interpreters work.

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Toby A Inkster]

Jerry Stuckle wrote:

Unless you have implemented a PHP optimizer, every PHP file is
interpreted every time you load the file. There is no intermediate code.

There normally *is* an intermediate form, but it's discarded after each
execution unless you have a PHP cache, such as eAccelerator.

That is, on each execution, the PHP interpreter:

1. Opens up the file;
2. Tokenises it, storing the token stream in memory;
3. Parses it into a form of byte code, storing that in
memory too; then
4. Executes the byte code.

Most smart interpreters (and I assume PHP is included here) will also
perform a bit of code optimisation around stage 3 too. Code optimisation
trades off execution time for parsing time, so interpreters (optimise once,
run once) tend not to optimise as much as compilers (optimise once, run
many) do.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.12-12mdksmp, up 30 days, 12:01.]

Parsing an HTML Table with PEAR's XML_HTTPSax3
http://tobyinkster.co.uk/blog/2007/0...table-parsing/