Commit: e0c4f87a897e005f5927baa8a747e6266d052813 Author: krakjoe <joe.watk...@live.co.uk> Fri, 22 Nov 2013 13:49:35 +0000 Parents: 4fd2edbeb42b842d0c7cdb00363c7b09aa89b906 Branches: PHP-5.6
Link: http://git.php.net/?p=php-src.git;a=commitdiff;h=e0c4f87a897e005f5927baa8a747e6266d052813 Log: another tut Changed paths: A tutorials/simples.md Diff: diff --git a/tutorials/simples.md b/tutorials/simples.md new file mode 100644 index 0000000..d8b53d6 --- /dev/null +++ b/tutorials/simples.md @@ -0,0 +1,132 @@ +Simples +======= +*Everything is simple ...* + +It is easy to imagine that debugging a whole web application might be difficult, in a console program, in fact this is not the case: + +A web application is just an instance of the PHP interpreter with some very specific super globals set. + +With everything in the correct place, your web application has no clue that it being served not to a client, but to you, probably in your underwear. + +With the facts established, you can use phpdbg to debug anything that is PHP, with a bit of cleverness in the right places. + +Very Simple +=========== +*A good starting place ...* + +``` +phpdbg -e/path/to/my/script.php +``` + +The command above will result in a phpdbg console that has executed *.phpdbginit* (if it exists) and is ready to compile, inspect, step through +and execute the code contained in */path/to/my/script.php* + +The first thing to do upon being presented with the console, is decide what to break for ... + +Many options exist for choosing (and setting) breakpoints: + +``` +phpdbg> b phpdbg::isGreat +phpdbg> b phpdbg_is_great +``` + +The commands above will be the most common for most developers; that is, specifying the entry point of a function or method on which to break execution. + +Introspection of code is supported on the console, for anything that is compiled, if help is required remembering the name of a particular method then issue: + +``` +phpdbg> compile +phpdbg> print class myClassName +``` + +Introspection doesn't only provide you with names, but the addresses of every opcode in every statement, which you may use to specify with as much precision as +is possible where to break execution. + +**There is a print command for particular methods, useful if a class is very large and your screen is not !** + +At this point, break points are set; the next thing to do is issue the run command: + +``` +phpdbg> run +``` + +This will cause execution of the context, if a breakpoint is reached, the interactive console returns such that more commands can be issued. + +When a breakpoint is reached, several options for continuation exist: + + - step through every instruction + - run past the end of the stack + - run to the end of the stack + +*Q: WTF is a stack?* + +*A: Generally the current codepath, more precisely: current function, method or file* + +Just quickly; an explanation of what "to" and "past" the end of a "stack" means: + +Assuming there is a break set for *my_function_somewhere* in the following code: + +``` +function my_function_somewhere($input = array()) /* break here on entry to the function */ +{ + /* ... the stack ... */ + + if (count($input)) + { + /* to -> */ return $input[1]; + } + else + { + /* to -> */ return rand(1, 100); + } +} + +/* past -> */ $result = my_function_somewhere(); +if ($result) +{ + /* and so on */ + var_dump($result); +} +``` + +The commands *finish* and *leave*, run *past* and *to* the end of the stack respecitively. + +**Note: the finish command does not automatically break; to break past the end of the stack enable stepping before issuing finish, the leave command breaks implicitly** + +On with execution ... +===================== +*Stepping, slowly, is sometimes the way forward ...* + +Should you want to inspect what happens during the execution of the stack, enable stepping: + +``` +phpdbg> step 1 +``` + +In case it wasn't obvious, the next thing to do is nearly always *next*: + +``` +phpdbg> next +``` + +Which will cause the vm to assume control and continue execution until the next break point, or completion. + +Stepping through every single instruction is not usually beneficial, issue: + +``` +phpdbg> step 0 +``` + +To disable stepping again, and only interrupt execution for breakpoints. + +As hard as it gets ... +====================== +*Web Applications* + +As mentioned, a web application is only a script executing with some specific super globals set; + +**The mocking of any web request just requires that you set the super globals of the script accordingly** + +We refer to this as "bootstrapping", mostly because I have always wanted a genuine reason to use that word. + +See the example, for help with bootstrapping ... -- PHP CVS Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
