string_capacity

A string builder where the code to calculate the capacity is the same as the code to write the string.

Sometimes you have some complex code that would be a bit of a pain to calculate the capacity of or could easily lead to getting out of sync with the implementation. This crate makes that easier.

let text = StringBuilder::build(|builder| {
  for (i, import_module) in import_modules.iter().enumerate() {
    builder.append("// ");
    builder.append(i);
    builder.append(" import\n");
    builder.append("import \"");
    builder.append(import_module);
    builder.append("\";\n");
  }
})?;

Behind the scenes it runs the closure once to compute the capacity and a second time to write the string.

Features

1. The builder prevents adding owned strings—only references.

• This helps to prevent accidentally allocating strings multiple times in the closure.

1. Errors when capacity cannot be reserved.
2. Types other than string references can be provided.

• Numbers get written with the itoa crate.

Tips

• Do any necessary allocations before running the closure.
• Measure before and after using this crate to ensure you're not slower.
• Probably don't use this crate if computing the capacity is simple.
  • Though maybe it will create more maintainable code, so measure and see.