23 — Modules: split your program into files

One file works for a small program. As a project grows, splitting it into modules keeps each file focused. NME imports only the names you list, so every module has a clear interface and nothing else leaks between files.

#Steps

1. Put shared functions in a module file. A module is an ordinary .nme file that defines values instead of running a whole program:

   # shapes.nme
   def rect(width, height):
       return width * height
   
   
   def circle(radius):
       return 3.14 * radius * radius
   

   copyrun it →

2. Import the names you need in the main program:

   # area.nme
   from "shapes.nme" import rect, circle
   
   show rect(4, 5)
   show circle(2)
   

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3. Run the main program; NME finds shapes.nme next to it:

   nme run area
   

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   20
   12.56
   

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   The ready-made pair lives in examples/modules/ — area.nme and shapes.nme, with _ko Korean twins.

4. The import name list is the interface. Only rect and circle cross into area.nme; anything else in the module stays private. Imported names can be used in sentences like any other value:

   from "shapes.nme" import rect
   show rect(3, 7)
   

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#Rules to remember

• The module file sits next to the main program.
• The file name is a Python identifier: shapes.nme, not my-shapes.nme.
• Imports can chain: a module may import another module.
• nme check and nme build check imported modules too.

#Try it yourself

Add a perimeter(width, height) function to shapes.nme, import it in area.nme, and show the perimeter of a 4 by 5 rectangle.

#What you learned

• from "helper.nme" import name1, name2 imports only the listed names.
• The module is a normal .nme file in the same folder.
• Imported names work in sentences and calls like local values.
• A clear interface means no hidden global state between files.