#36058: Refactor SpatialRefSysMixin.srs Property for Improved Efficiency and
Clarity
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Reporter: Arnaldo Govene | Owner: (none)
Type: Cleanup/optimization | Status: assigned
Component: GIS | Version: 5.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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The srs property in the `SpatialRefSysMixin` class has several issues that
can be addressed to improve code efficiency, maintainability, and
adherence to best practices. The following points highlight the concerns:
**1. Recursive Calls:**
The property uses return self.srs within the try blocks. This introduces
recursion, which could lead to stack overflow in edge cases or unexpected
behavior. The recursive call to self.srs results in the function calling
itself indefinitely, leading to a potential infinite loop.
Current Code:
{{{
try:
self._srs = gdal.SpatialReference(self.wkt)
return self.srs # Recursive call
except Exception as e:
msg = e
}}}
**2. Error Handling:**
The msg variable is overwritten in the second try block without being
utilized after the first block, making error reporting ambiguous. This
results in the final error message only reflecting the second exception,
losing context from the first one.
Current Code:
{{{
try:
self._srs = gdal.SpatialReference(self.wkt)
return self.srs
except Exception as e:
msg = e # First exception caught
try:
self._srs = gdal.SpatialReference(self.proj4text)
return self.srs
except Exception as e:
msg = e # Second exception overwrites the first
}}}
**Proposal:**
**1. Remove Recursive Calls:**
Replace return self.srs with return `self._srs.clone()` fo avoid recursion
and improve clarity.
**Refactored Code:**
{{{
if hasattr(self, "_srs"):
return self._srs.clone() # Return the clone of the cached object
}}}
**2. Improve Error Reporting:**
Capture and differentiate between errors raised during the initialization
from WKT and PROJ.4. Ensure that both error messages are included in the
final exception for better clarity and debugging.
Refactored Code:
{{{
try:
self._srs = gdal.SpatialReference(self.wkt)
return self._srs.clone()
except Exception as e:
wkt_error = f"Error initializing from WKT: {str(e)}"
try:
self._srs = gdal.SpatialReference(self.proj4text)
return self._srs.clone()
except Exception as e:
proj4_error = f"Error initializing from PROJ.4: {str(e)}"
raise Exception(f"Could not get OSR SpatialReference. WKT Error:
{wkt_error} | PROJ.4 Error: {proj4_error}")
}}}
**Expected Outcome:**
- By removing recursion and directly returning a cloned object, we avoid
unnecessary function calls and improve performance.
- With differentiated error messages, it becomes easier to diagnose issues
with the WKT or PROJ.4 initialization.
--
Ticket URL: <https://code.djangoproject.com/ticket/36058>
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