Python try, except and Clause Ordering
Objective 4.4 is the basics of Python exception handling, and there are four keywords: try, except, else, finally. The syntax is small and the ordering rule is the whole subject - clauses are tested top to bottom and the first matching one wins, so a broad clause above a narrow one makes the narrow one dead code, exactly as an elif chain does.
Exceptions Guide 24 of 26 Intermediate
- OSUbuntu 26.04 LTS
- Python3.14.4
- pip25.1.1
- TimeAbout 16 min
Python 3.14 allows except A, B: without parentheses (PEP 758). The exam does not - see guide 3. Every example here uses the parenthesised form, which is correct on every release.
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| RUNNER01 | 192.168.0.27 | Ubuntu 26.04 LTS | Python 3.14.4 - the only machine this path needs | 2 Core | 4 GB | 50 GB |
This guide includes
Use this for the exception-handling objective. This matters because clauses are tested top to bottom and the first match wins - so a general clause above a specific one swallows everything and the specific clause never runs.
- writing the smallest
try, and seeing that an unmatched clause does not help - ordering specific before general, then reversing it to watch it break
- naming several types in one clause, and adding
elseandfinally - meeting the bare
except, and what else it catches - seeing what the
tryblock leaves unfinished when it raises part-way
Before you start
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The smallest try
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A clause that does not match does not help
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Ordering: specific before general
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The same clauses in the wrong order
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One clause for several types, plus else and finally
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The bare except
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What the try block does not finish
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What the exam does with this objective