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# Module
## Import
The import statement is a syntax sugar for requiring a module or help extracting items from an imported module. The imported items are const by default.
```yuescript
-- used as table destructuring
do
import insert, concat from table
-- report error when assigning to insert, concat
import C, Ct, Cmt from require "lpeg"
-- shortcut for implicit requiring
import x, y, z from 'mymodule'
-- import with Python style
from 'module' import a, b, c
-- shortcut for requring a module
do
import 'module'
import 'module_x'
import "d-a-s-h-e-s"
import "module.part"
-- requring module with aliasing or table destructuring
do
import "player" as PlayerModule
import "lpeg" as :C, :Ct, :Cmt
import "export" as {one, two, Something:{umm:{ch}}}
```
<YueDisplay>
```yue
-- used as table destructuring
do
import insert, concat from table
-- report error when assigning to insert, concat
import C, Ct, Cmt from require "lpeg"
-- shortcut for implicit requiring
import x, y, z from 'mymodule'
-- import with Python style
from 'module' import a, b, c
-- shortcut for requring a module
do
import 'module'
import 'module_x'
import "d-a-s-h-e-s"
import "module.part"
-- requring module with aliasing or table destructuring
do
import "player" as PlayerModule
import "lpeg" as :C, :Ct, :Cmt
import "export" as {one, two, Something:{umm:{ch}}}
```
</YueDisplay>
## Import Global
You can import specific globals into local variables with `import`. When importing a chain of global variable accessings, the last field will be assigned to the local variable.
```yuescript
do
import tostring
import table.concat
print concat ["a", tostring 1]
```
<YueDisplay>
```yue
do
import tostring
import table.concat
print concat ["a", tostring 1]
```
</YueDisplay>
### Automatic Global Variable Import
You can place `import global` at the top of a block to automatically import all names that have not been explicitly declared or assigned in the current scope as globals. These implicit imports are treated as local consts that reference the corresponding globals at the position of the statement.
Names that are explicitly declared as globals in the same scope will not be imported, so you can still assign to them.
```yuescript
do
import global
print "hello"
math.random 3
-- print = nil -- error: imported globals are const
do
-- explicit global variable will not be imported
import global
global FLAG
print FLAG
FLAG = 123
```
<YueDisplay>
```yue
do
import global
print "hello"
math.random 3
-- print = nil -- error: imported globals are const
do
-- explicit global variable will not be imported
import global
global FLAG
print FLAG
FLAG = 123
```
</YueDisplay>
## Export
The export statement offers a concise way to define modules.
### Named Export
Named export will define a local variable as well as adding a field in the exported table.
```yuescript
export a, b, c = 1, 2, 3
export cool = "cat"
export What = if this
"abc"
else
"def"
export y = ->
hallo = 3434
export class Something
umm: "cool"
```
<YueDisplay>
```yue
export a, b, c = 1, 2, 3
export cool = "cat"
export What = if this
"abc"
else
"def"
export y = ->
hallo = 3434
export class Something
umm: "cool"
```
</YueDisplay>
Doing named export with destructuring.
```yuescript
export :loadstring, to_lua: tolua = yue
export {itemA: {:fieldA = 'default'}} = tb
```
<YueDisplay>
```yue
export :loadstring, to_lua: tolua = yue
export {itemA: {:fieldA = 'default'}} = tb
```
</YueDisplay>
Export named items from module without creating local variables.
```yuescript
export.itemA = tb
export.<index> = items
export["a-b-c"] = 123
```
<YueDisplay>
```yue
export.itemA = tb
export.<index> = items
export["a-b-c"] = 123
```
</YueDisplay>
### Unnamed Export
Unnamed export will add the target item into the array part of the exported table.
```yuescript
d, e, f = 3, 2, 1
export d, e, f
export if this
123
else
456
export with tmp
j = 2000
```
<YueDisplay>
```yue
d, e, f = 3, 2, 1
export d, e, f
export if this
123
else
456
export with tmp
j = 2000
```
</YueDisplay>
### Default Export
Using the **default** keyword in export statement to replace the exported table with any thing.
```yuescript
export default ->
print "hello"
123
```
<YueDisplay>
```yue
export default ->
print "hello"
123
```
</YueDisplay>
|
