Debug technics

• mix of print_r and d custom function that add a die and other stuff The behavior is different than dpm because it's printed on the script page and not on the following one. the d() function is here https://gist.github.com/4060502

Lister tous les hook appelé par drupal dans drupal 7 includes/modules.inc

• Integrate backtrace to drupal_set_message
  Lullabot post that explain how to backtrace when an error occure http://www.lullabot.com/articles/quick-and-dirty-debugging

• Lister les différents hook appelés Changer la fonction d'invocation des hooks situés includes/module.inc:815:function module_invoke_all($hook) { Code on gist https://gist.github.com/7ae97f626eb1629aaa38

• Lister les appels de fonction (backtrace)

print "<pre>";
print_r(debug_backtrace());
print "</pre>";

To print the calling function without the arguments passsed from function to function

print "<pre>";
print_r(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS));
print "</pre>";

• Debug the user_access function
  Display the permission string return FALSE

if (!$perm[$account->uid][$string]){print_r($string . '<br>');}

• How to know a template is being used Just place a d('are you in used'); If it's in used, a white screen will show with this message

• Recursion in not the end dpm
  When using devel, it occure that a element is shown as recursion. To see what's inside, make an other dpm with only this sub element key For exemple if writing dpm($form) you see $form['view'] show recursion

you can write write dpm($form['view']); to see what's inside

• Difference between debuging function in php var_dump , var_export , print_r
  http://stackoverflow.com/questions/5039431/difference-between-var-dump-var-export-print-r

• Output all defined variables
  When in a template and we don't know which variables are defined in this context, we can use a php function get_defined_vars http://php.net/manual/en/function.get-defined-vars.php

• debug an auto complete
  An autocomplete don't retrieve node's title we expected, just change it to select list to see what's are available choices

• debug the creation of a db schema
  The schema is installed only for the first installation of a module. So If it does'nt pass the first time, it's necessary to disable + install the module And then reinstall it. A trick could be to call drupal_install_schema function from a hook init so you can debug database installation without doing those boring steps