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81 lines
1.3 KiB
Markdown
81 lines
1.3 KiB
Markdown
# module
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Erg allows you to think of the file itself as a single record. This is called a module.
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```python: foo.er
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# foo.er
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.i = 1
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```
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```python
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# Defining the foo module is almost the same as defining this record
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foo = {.i = 1}
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```
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```python: bar.er
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# bar.er
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foo = import "foo"
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print! foo # <module 'foo'>
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assert foo.i == 1
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```
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Since module types are also record types, deconstruction assignment is possible.
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```python
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{sin; cos; ...} = import "math"
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```
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## module visibility
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```console
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└─┬ ./src
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├─ lib.er
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├─ foo.er
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├─bar.er
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└─┬ bar
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├─ baz.er
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└─ qux.er
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```
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## circular dependencies
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Erg allows you to define circular dependencies between modules.
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```python
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# foo.er
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bar = import "bar"
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print! bar.g 1
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.f x = x
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```
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```python
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# bar.er
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foo = import "foo"
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print! foo.f 1
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.g x = x
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```
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However, variables created by procedure calls cannot be defined in circular reference modules.
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This is because Erg rearranges the order of definitions according to dependencies.
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```python
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# foo.er
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bar = import "bar"
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print! bar.x
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.x = g!(1) # ModuleError: variables created by procedure calls cannot be defined in circular reference modules
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```
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```python
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# bar.er
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foo = import "foo"
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print! foo.x
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.x = 0
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```
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<p align='center'>
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<a href='./23_closure.md'>Previous</a> | <a href='./25_object_system.md'>Next</a>
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</p>
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