# python: declare_var
URL: https://generaltranslation.com/en-GB/docs/python/api/declare-var.mdx
---
title: declare_var
description: API reference for the declare_var function
---

## Overview

`declare_var` wraps a dynamic value with a GT variable marker so that translation engines can preserve the variable in the translated output.

```python
from gt_flask import declare_var  # or from gt_fastapi import declare_var

greeting = declare_var("Alice", name="user")
```


## Reference

### Parameters

<TypeTable
  type={{
  "variable": {
    type: 'str | int | float | bool | None',
    description: 'The value to embed as a non-translatable variable.',
  },
  "name?": {
    type: 'str',
    optional: true,
    description: 'Optional human-readable variable name.',
  },
}}
/>

### Returns

`str` — an ICU select construct that wraps the value as a GT variable marker.

***

## Notes

* Use `declare_var` for values that change at runtime (e.g. user names, counts).
* See also [`derive`](/docs/python/api/derive) for values known at build time.
* Use [`decode_vars`](/docs/python/api/decode-vars) to extract the variables back from a marked string.