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46 lines
890 B
Markdown
46 lines
890 B
Markdown
# Temporary mutability
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## Description
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Often it is necessary to prepare and process some data, but after that data are
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only inspected and never modified. The intention can be made explicit by redefining
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the mutable variable as immutable.
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It can be done either by processing data within nested block or by redefining
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variable.
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## Example
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Say, vector must be sorted before usage.
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Using nested block:
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```rust,ignore
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let data = {
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let mut data = get_vec();
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data.sort();
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data
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};
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// Here `data` is immutable.
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```
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Using variable rebinding:
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```rust,ignore
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let mut data = get_vec();
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data.sort();
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let data = data;
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// Here `data` is immutable.
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```
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## Advantages
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Compiler ensures that you don't accidentally mutate data after some point.
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## Disadvantages
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Nested block requires additional indentation of block body.
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One more line to return data from block or redefine variable.
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