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Tech Tip: When to use the "Use (Storage)" code block
PRODUCT: 4D | VERSION: 17 | PLATFORM: Mac & Win
Published On: April 18, 2019
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There are certain scenarios where the "Use (Storage)" code block is required and other scenarios where it is not necessary. For example, a new shared collection is initialized and the collection is about to be modified.

// Initialize new shared collection
Use (Storage)
   Storage.test:=New shared collection
End use


There are two ways to modify the existing shared collection or shared object: member functions or assignment. In this example, if the shared collection is modified using a member function like collection.push, only the Use (Storage.test) code block is required as shown below:

// Use (Storage) is not required since push method directly modifies the collection
Use (Storage.test)
   Storage.test.push(1)
End use


If the shared collection/object is reassigned to a new value, both Use (Storage) and Use (Storage.test) are required.

// Both use code blocks are required when assigning new values
Use (Storage)
   Use (Storage.test)
      Storage.test:=New shared collection
   End use
End use


Otherwise, using only Use (Storage.test) on reassignment will result in an error.

// Error
Use (Storage.test)
   Storage.test:=New shared collection
End use