Importing modules

• The import statement makes all names of a module available, e.g.:

  import time
  time.sleep(1)
  

  A function that has been imported using this syntax has to be fully qualified when invoked, modulePath.functionName.

• The import-as statement makes all names of a module available and assigns a short-hand to the module path:

  import sardana.macroserver.macro as ms
  

  This allows you to refer to the Type variable using ms.Type instead of sardana.macroserver.macro.Type.

• The from-import statement imports names into the importing modules symbol table. To import single names:

  from time import sleep
  sleep(1)
  

  To import all module names:

  from time import *
  

  Notice that the from-import imported names are referenced without leading module path, e.g. 'sleep()' NOT 'time.sleep()'.

• Comparing import and from-import we see that the latter reduces the typing effort. However, considering bigger software projects the modulePath.functionName notation enhances the readability of the code. Therefore the import syntax is recommended, import-as is of course also ok.

• The function dir() or dir( someObj) returns a list of names belonging to the respective scope. It is well suited to understand the effect of import and from-import statements.

• import and from are executed once. They cannot be used to refresh modules that have already been loaded.

• The built-in function reload() re-loads a module which has been imported before. Note that the module is specified omitting quotes.

  import HasyUtils
  ...
  reload( HasyUtils)
  

• Importing sub-packages is explained in 4.1.

• The dictionary sys.modules contains the loaded modules.

• A module name becomes an attribute after the import.