Editing Octave style guide
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There is no fixed line length. In general, strive for clarity and readability and use your own judgement. | There is no fixed line length. In general, strive for clarity and readability and use your own judgement. | ||
Everyone has access to monitors with more than 80 columns, but even so, exceptionally long lines can be hard to read. | Everyone has access to monitors with more than 80 columns, but even so, exceptionally long lines can be hard to read. But, keeping code together on one line that is logically one unit does improve readability. | ||
=== Indentation === | === Indentation === | ||
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Use only spaces, and indent 2 spaces at a time. | Use only spaces, and indent 2 spaces at a time. | ||
Absolutely | We use spaces for indentation. Absolutely do not use tabs in your code. | ||
You should probably set your editor to emit spaces when you hit the tab key. | |||
=== Whitespace === | === Whitespace === | ||
When calling functions, put spaces after commas and before the calling | When calling functions, put spaces after commas and before the calling | ||
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Here, putting spaces after {{codeline|sin}}, {{codeline|cos}} would result in a | Here, putting spaces after {{codeline|sin}}, {{codeline|cos}} would result in a | ||
parse error. | parse error. | ||
For indexing expressions, do ''not'' put a space after the | For indexing expressions, do ''not'' put a space after the | ||
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<pre>A([1:i-1;i+1:n], XI(:,2:n-1))</pre> | <pre>A([1:i-1;i+1:n], XI(:,2:n-1))</pre> | ||
When constructing matrices, prefer using the comma rather than the space to | When constructing matrices, prefer using the comma rather than the space to | ||
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</pre> | </pre> | ||
However, if the matrix is large or the indentation makes it clear | However, if the matrix is large or the indentation makes it clear the comma | ||
may be dropped. | may be dropped. | ||
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44.04 55.05 6.06]; | 44.04 55.05 6.06]; | ||
</pre> | </pre> | ||
Do include spaces around all binary arithmetic operators, for example | Do include spaces around all binary arithmetic operators, for example | ||
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</pre> | </pre> | ||
An exception is for extremely simple expressions like | An exception is for extremely simple expressions like <pre>n+1</pre>, in | ||
particular when used as an argument to a function or as part of an indexing | |||
<pre>n+1</pre> | expression. For example, you may write | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
Another exception is for complex arithmetic expressions. | Another exception is for complex arithmetic expressions. It may improve | ||
readability to omit spaces around higher precedence operators, for example | |||
<pre> | <pre> | ||
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When you encounter an error condition, call the function {{codeline|error}} | When you encounter an error condition, call the function {{codeline|error}} | ||
(or {{codeline|print_usage}}). The {{codeline|error}} and {{codeline|print_usage}} functions | (or {{codeline|print_usage}}). The {{codeline|error}} and {{codeline|print_usage}} functions | ||
do not return. | do not return. It is customary to prefix the error message | ||
with the name of the function that generated it. For example: | |||
It is customary to prefix the error message with the name of the function that generated it. For example: | |||
<pre>error ("my_cool_function: input A must be a matrix");</pre> | <pre>error ("my_cool_function: input A must be a matrix");</pre> | ||
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Because the function call to {{codeline|error}} is one code unit, prefer keeping the message on one line even if the message itself is long. | Because the function call to {{codeline|error}} is one code unit, prefer keeping the message on one line even if the message itself is long. | ||
Octave has several functions that produce error messages according to the Octave guidelines. Consider using {{codeline|inputParser}} | Octave has several functions that produce error messages according | ||
to the Octave guidelines. Consider using {{codeline|inputParser}} | |||
and {{codeline|validateattributes}}. | and {{codeline|validateattributes}}. | ||
== Naming == | == Naming == | ||
Use lowercase names if possible. Uppercase is acceptable for variable names consisting of 1-2 letters. Do not use mixed case | Use lowercase names if possible. Uppercase is acceptable for variable | ||
names consisting of 1-2 letters. Do not use mixed case names. Function | |||
names must be lowercase. Function names are global, so choose them | |||
wisely. | |||
=== General naming functions === | === General naming functions === | ||
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=== Function names === | === Function names === | ||
For most public functions we are limited by Matlab compatibility. Use whatever name Matlab | For most public functions we are limited by Matlab compatibility. Use | ||
whatever name Matlab choose. | |||
There are exceptions to this: | For functions that are not present in Matlab favour the use of underscores. | ||
For example, {{codeline|base64_decode}}, {{codeline|common_size}}, or | |||
{{codeline|compare_versions}}. There are exceptions to this: | |||
; Matching C functions | ; Matching C functions | ||
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Avoid reusing the names of other functions as local variable names. For | Avoid reusing the names of other functions as local variable names. For | ||
example, avoid naming local variables {{codeline|abs}}, | example, try to avoid naming local variables {{codeline|abs}}, | ||
{{codeline|log}}, or {{codeline|pow}}. These | {{codeline|log}}, or {{codeline|pow}}. These functions may be used in a | ||
later change and may lead to confusing errors. | |||
An exception is the use of {{codeline|i}} and {{codeline|j}} as loop indices. | An exception is the use of {{codeline|i}} and {{codeline|j}} as loop indices. | ||
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=== # or % === | === # or % === | ||
Always use {{Codeline|#}} to write comments | Always use {{Codeline|#}} to write comments. | ||
Absolutely do not use {{codeline|%#}} or mix {{codeline|%}} and {{codeline|#}} | Absolutely do not use {{codeline|%#}} or mix {{codeline|%}} and {{codeline|#}} |