GDAL Version Specification

Oct 13, 2025 by leolavanderia.com.br 31 views

Introduction

When working with environment collector plugins, it can be challenging to populate environment variables that are referenced in pyproject.toml. In this article, we will explore the issue of using environment variables as context variables in pyproject.toml and discuss possible solutions.

The Problem

We are using an environment collector plugin to populate an environment variable GDAL_VERSION_SPECIFICATION. This environment variable is referenced in pyproject.toml as follows:

dependencies = [
    "gdal{env:GDAL_VERSION_SPECIFICATION}",
]

However, the environment collector plugin only allows real environment variables to be used for context substitution. This means that we cannot use the env-vars dictionary populated by the environment collector plugin as context variables.

The Current Workaround

To overcome this limitation, we are currently setting a real environment variable in our environment collector plugin as a workaround:

os.environ.setdefault("GDAL_VERSION_SPECIFICATION", some_value)

This approach is fragile and relies on the collector plugin and the context substitution being executed within the same process.

The Desired Solution

The obvious solution is to let the context substitution peek into the env-vars dictionary of the current environment. However, this information is not handed over to the context substitution at the moment.

Possible Solutions

There are several possible solutions to this issue:

1. Modify the Environment Collector Plugin

One possible solution is to modify the environment collector plugin to hand over the env-vars dictionary to the context substitution. This would allow us to use environment variables as context variables in pyproject.toml.

2. Use a Custom Context Substitution

Another possible solution is to use a custom context substitution that can peek into the env-vars dictionary. This would require modifying the context substitution code to access the env-vars dictionary.

3. Use a Different Approach

A third possible solution is to use a different approach to populate environment variables in pyproject.toml. For example, we could use a separate file to store the environment variables and then reference them in pyproject.toml.

Conclusion

In conclusion, using environment variables as context variables in pyproject.toml is not currently supported by the environment collector plugin. However, there are several possible solutions to this issue, including modifying the environment collector plugin, using a custom context substitution, or using a different approach to populate environment variables.

Future Work

To resolve this issue, we will need to modify the environment collector plugin to hand over the env-vars dictionary to the context substitution. This will require collaboration with the maintainers of the environment collector plugin.

Example Use Cases

Here are some example use cases for using environment variables as context variables in pyproject.toml:

GDAL Version Specification: We can use an environment variable to specify the version of GDAL to use in our project.
Dependency Versioning: We can use environment variables to specify the version of dependencies in our project.
Configuration Variables: We can use environment variables to store configuration variables for our project.

Code Examples

Here are some code examples that demonstrate how to use environment variables as context variables in pyproject.toml:

Environment Collector Plugin: We can use the environment collector plugin to populate an environment variable GDAL_VERSION_SPECIFICATION:

env_dict = env_entry.setdefault("env-vars", {}) env_dict.setdefault("GDAL_VERSION_SPECIFICATION", some_value)

*   **Context Substitution**: We can use a custom context substitution to peek into the `env-vars` dictionary:
    ```python
def context_substitution(env_vars):
    return env_vars.get("GDAL_VERSION_SPECIFICATION")

Pyproject.toml: We can reference the environment variable in pyproject.toml:

dependencies = [ "gdalenvGDAL_VERSION_SPECIFICATION", ]


**References**
--------------

*   [Environment Collector Plugin](https://hatch.pypa.io/latest/plugins/environment-collector/reference/)
*   [Context Substitution](https://github.com/pypa/hatch/blob/d81790e47faaa145d1b6ad2fabc73327cc5d62a2/backend/src/hatchling/utils/context.py#L85)
*   [Pyproject.toml](https://github.com/pypa/hatch/blob/master/backend/src/hatchling/utils/context.py)<br/>
**Environment Collector Plugin: Environment Variables Cannot Be Used as Context Variables in Pyproject.toml - Q&A**
===========================================================

**Q: What is the environment collector plugin?**
--------------------------------------------

A: The environment collector plugin is a tool used to populate environment variables in `pyproject.toml`. It allows you to define environment variables and their values in a separate file, which can then be referenced in `pyproject.toml`.

**Q: Why can't I use environment variables as context variables in pyproject.toml?**
--------------------------------------------------------------------------------

A: The environment collector plugin only allows *real* environment variables to be used for context substitution. This means that you cannot use the `env-vars` dictionary populated by the environment collector plugin as context variables.

**Q: What is the current workaround for this issue?**
------------------------------------------------

A: The current workaround is to set a *real* environment variable in your environment collector plugin as a workaround:
```python
os.environ.setdefault("GDAL_VERSION_SPECIFICATION", some_value)

This approach is fragile and relies on the collector plugin and the context substitution being executed within the same process.

Q: What are the possible solutions to this issue?

A: There are several possible solutions to this issue:

Modify the Environment Collector Plugin: Modify the environment collector plugin to hand over the env-vars dictionary to the context substitution.
Use a Custom Context Substitution: Use a custom context substitution that can peek into the env-vars dictionary.
Use a Different Approach: Use a different approach to populate environment variables in pyproject.toml.

Q: How can I modify the environment collector plugin to hand over the env-vars dictionary to the context substitution?

A: To modify the environment collector plugin to hand over the env-vars dictionary to the context substitution, you will need to collaborate with the maintainers of the environment collector plugin.

Q: What are some example use cases for using environment variables as context variables in pyproject.toml?

A: Here are some example use cases for using environment variables as context variables in pyproject.toml:

GDAL Version Specification: Use an environment variable to specify the version of GDAL to use in your project.
Dependency Versioning: Use environment variables to specify the version of dependencies in your project.
Configuration Variables: Use environment variables to store configuration variables for your project.

Q: How can I use a custom context substitution to peek into the env-vars dictionary?

A: To use a custom context substitution to peek into the env-vars dictionary, you can define a function that takes the env-vars dictionary as an argument and returns the value of the environment variable:

def context_substitution(env_vars):
    return env_vars.get("GDAL_VERSION_SPECIFICATION")

Q: What are some best practices for using environment variables as context variables in pyproject.toml?

A: Here are some best practices for using environment variables as context variables in pyproject.toml:

Use a consistent naming convention: Use a consistent naming convention for your environment variables.
Document your environment variables: Document your environment variables and their values.
Use a secure method to store sensitive information: Use a secure method to store sensitive information, such as encryption.

Q: What are some common pitfalls to avoid when using environment variables as context variables in pyproject.toml?

A: Here are some common pitfalls to avoid when using environment variables as context variables in pyproject.toml:

Do not use hardcoded values: Do not use hardcoded values for your environment variables.
Do not use sensitive information: Do not use sensitive information, such as passwords or API keys, as environment variables.
Do not use environment variables for sensitive information: Do not use environment variables for sensitive information, such as encryption keys.