First matching item

When writing code one often needs to grab the first item in a collection that has certain characteristics. For example, one may have a list of Student objects and need to fetch the one with a certain id.

The task is trivial: loop through the list and compare each student's id until a match is found or all the students in the list have been inspected, whichever comes first.

In the past, I've tended to take advantage of return statements to exit the loop as soon as a match is found. The examples here are in Python, but the same patterns apply to other languages.

def student_by_id(students, id):
    for student in students:
        if student.id == id:
            return student
    return None

This appoach strikes me as inelegant when the function is called in one place only. Today a different approached occurred to me.

student = None
for student in students:
    if student.id == id:
        break
    student = None

Here, we break out of the loop as soon as a match is found, preserving the student of interest in the variable student. Each time through the loop student is cleared to ensure that student is empty once we've finished looping if there are no matches.

The first line is required to handle empty lists.

I think I'll use this approach from time to time. Let me know if you're aware of another option.

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Comments

student = next((student for student in students if student.id == id), None)

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