Difference between revisions of "Coding best practices"

Line 4: Line 4:
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">There are code standards and conventions available depending on the language you are using and sometimes also conventions adopted for specific&nbsp;collaborative projects. While below we provide a few links to these, here&nbsp;we are just going to focus on&nbsp;some basic tips that can help you making&nbsp;your code more readable and safer from bugs. These can be applied to any language.</span></span> &nbsp;
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">There are code standards and conventions available depending on the language you are using and sometimes also conventions adopted for specific&nbsp;collaborative projects. While below we provide a few links to these, here&nbsp;we are just going to focus on&nbsp;some basic tips that can help you making&nbsp;your code more readable and safer from bugs. These can be applied to any language.</span></span> &nbsp;
  
Naming
+
=== <span style="font-size:large;">'''<span style="font-family:Arial,Helvetica,sans-serif;">Naming</span>'''</span> ===
 +
 
 +
==== '''<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Avoid reserved keywords and names of common functions names</span></span>''' ====
 +
 
 +
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">[https://realpython.com/lessons/reserved-keywords/ Reserved keywords] are words that are used for special functionalities as "if", "import" etc., so they cannot use to name anything else. Any other word can be used as a name but there are some that is still best to avoid, common examples are 'file'</span></span>
 +
 
 +
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">There are also some that can be used as a name,like 'file', 'list', 'dict' , but that are already names of&nbsp;existing functions. This will of course also depend on which modules you are using and how you import them.</span></span>
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Use long and descriptive names for variables and functions'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Use long and descriptive names for variables and functions'''</span></span> ====
  
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">There is no advantage in using&nbsp;short names for variables and functions, it is good practice instead to use names that are descriptive, even if this will make them longer. Particularly for functions it is good to specify in the name what they do</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Ex for a function that calculates an anomaly use&nbsp;calculate_anomaly() rather than calc().</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">This also reduce the chances of using a reserved word**</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">NB If you're using an IDE to edit your code then you can auto complete the names</span></span> &nbsp; <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">**reserved words</span></span>
+
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">There is no advantage in using&nbsp;short names for variables and functions, it is good practice instead to use names that are descriptive, even if this will make them longer. Particularly for functions it is good to specify in the name what they do.</span></span>
 +
 
 +
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">For example for a function that calculates an anomaly use&nbsp;calculate_anomaly() rather than calc().</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">This also reduce the chances of using a reserved word.</span></span>
 +
 
 +
&nbsp;<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">NB If you're using an IDE to edit your code then you can easily auto complete the names</span></span>&nbsp;&nbsp;
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Use consistent naming across the code'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Use consistent naming across the code'''</span></span> ====
Line 21: Line 31:
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Whatever you choose&nbsp;try to be consistent, use the same conventions for the same type of objects.</span></span>
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Whatever you choose&nbsp;try to be consistent, use the same conventions for the same type of objects.</span></span>
  
Strutcture&nbsp;??
+
=== <span style="font-size:large;"><span style="font-family:Arial,Helvetica,sans-serif;">'''Code structure'''</span></span> ===
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Indents'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Indents'''</span></span> ====
  
&nbsp; <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Some languages like Python enforce indenting, but even where it is not necessary indenting your code can help outlining the code structure. Again try&nbsp;to be consistent either use tabs or spaces, some languages like python have a preference for spaces.</span></span>
+
&nbsp;<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Some languages like Python enforce indenting, but even where it is not necessary indenting your code can help outlining the code structure. Again try&nbsp;to be consistent either use tabs or spaces, some languages like python have a preference for spaces.</span></span>
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Comments'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Comments'''</span></span> ====
  
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''&nbsp;'''</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Comments are extremely useful to document what your code is doing. Again you do not need to comment every line, as that might actually made the code less redable. But it is a good practice to have:</span></span>
+
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Comments are extremely useful to document what your code is doing. Again you do not need to comment every line, as that might actually made the code less redable. But it is a good practice to have:</span></span>
  
 
*<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">&nbsp;a block of comments at the start of the code listing author, license,a a date for the last update,&nbsp;what the code does and how to use it.</span></span>  
 
*<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">&nbsp;a block of comments at the start of the code listing author, license,a a date for the last update,&nbsp;what the code does and how to use it.</span></span>  
Line 41: Line 51:
 
# Save output to file</nowiki>
 
# Save output to file</nowiki>
  
&nbsp; <span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">In this way you have a draft of your comments and you can work out the best structure, indivifduate blocks that can be included ina. function etc,&nbsp;before you even start coding. It can save you a lot of time.</span></span>
+
&nbsp;<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">In this way you have a draft of your comments and you can work out the best structure, individuate blocks that can be included ina. function etc,&nbsp;before you even start coding. It can save you a lot of time.</span></span>
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Subdive&nbsp;your code using functions or sub-modules'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''Subdive&nbsp;your code using functions or sub-modules'''</span></span> ====
  
&nbsp; <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Ideally a function should execute one coherent operation. As none of us it's a software developer we are not suggesting every line&nbsp;of code is a function , more than a logical block of lines should be included in a function. This is particularly true and useful if it's a block of code you might want to repeat in other parts of this same or others programs.</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Another good reason to enclose a block of code in a function it is to make it easier to add a test.</span></span> &nbsp; <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Use tests</span></span> &nbsp; <font face="Arial, Helvetica, sans-serif" size="3">It is a good idea to test at least critical parts of your code. You want to be sure that&nbsp;a&nbsp;calculation which is critical to your results, is producing consistent and correct results, no matter what changes you introduce to the same function or&nbsp;other part of your code.</font> <font face="Arial, Helvetica, sans-serif" size="3">No matter how many tests you are conducting it is hard to preview all the possible ways a code can be used and it is often the case that as soon as you sue a different set of data you are going to find some bugs. Every time you fix a bug make sure you are adding a test to capture it. So you will know if accidentally you re-introduce it later on.</font>
+
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Ideally a function should execute one coherent operation. As none of us it's a software developer we are not suggesting every line&nbsp;of code is a function , more than a logical block of lines should be included in a function. This is particularly true and useful if it's a block of code you might want to repeat in other parts of this same or others programs.</span></span> <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Another good reason to enclose a block of code in a function it is to make it easier to add a test.</span></span> &nbsp; <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Use tests</span></span> &nbsp; <font face="Arial, Helvetica, sans-serif" size="3">It is a good idea to test at least critical parts of your code. You want to be sure that&nbsp;a&nbsp;calculation which is critical to your results, is producing consistent and correct results, no matter what changes you introduce to the same function or&nbsp;other part of your code.</font> <font face="Arial, Helvetica, sans-serif" size="3">No matter how many tests you are conducting it is hard to preview all the possible ways a code can be used and it is often the case that as soon as you sue a different set of data you are going to find some bugs. Every time you fix a bug make sure you are adding a test to capture it. So you will know if accidentally you re-introduce it later on.</font>
 +
 
 +
==== DRY code ====
  
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''One statement per line'''</span></span> ====
 
==== <span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">'''One statement per line'''</span></span> ====
  
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Cramming a lot of instrcutions in one line of code won't make your code faster, just less readable. It will also make it more difficult to pinpoint what is causing an error if you have a few instructions in the same line.</span></span>
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Cramming a lot of instrcutions in one line of code won't make your code faster, just less readable. It will also make it more difficult to pinpoint what is causing an error if you have a few instructions in the same line.</span></span>
 
&nbsp;
 
  
 
==== '''<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">Keep your files a reasonable length</span></span>''' ====
 
==== '''<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">Keep your files a reasonable length</span></span>''' ====
 
&nbsp;
 
  
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Main message here is to be consistent and descriptive, in the end any conventions aim is to have consistency. Even&nbsp;if you are not using an established convention, being at least consistent across all of your codes will help making them more&nbsp;readable and re-usable.</span></span>
 
<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Main message here is to be consistent and descriptive, in the end any conventions aim is to have consistency. Even&nbsp;if you are not using an established convention, being at least consistent across all of your codes will help making them more&nbsp;readable and re-usable.</span></span>
  
Functions
+
=== '''<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">Functions</span></span>''' ===
  
==== '''<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">try to have only one exit point in a function</span></span>''' ====
+
==== '''<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">Try to have only one exit point in a function</span></span>''' ====
  
Return example
+
<span style="font-size:medium;"><span style="font-family:Arial,Helvetica,sans-serif;">Return example</span></span>
  
 
=== '''<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Style guides</span></span>''' ===
 
=== '''<span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:medium;">Style guides</span></span>''' ===

Revision as of 23:43, 8 July 2021

Template:Working on New page under construction

 

There are code standards and conventions available depending on the language you are using and sometimes also conventions adopted for specific collaborative projects. While below we provide a few links to these, here we are just going to focus on some basic tips that can help you making your code more readable and safer from bugs. These can be applied to any language.  

Naming

Avoid reserved keywords and names of common functions names

Reserved keywords are words that are used for special functionalities as "if", "import" etc., so they cannot use to name anything else. Any other word can be used as a name but there are some that is still best to avoid, common examples are 'file'

There are also some that can be used as a name,like 'file', 'list', 'dict' , but that are already names of existing functions. This will of course also depend on which modules you are using and how you import them.

Use long and descriptive names for variables and functions

There is no advantage in using short names for variables and functions, it is good practice instead to use names that are descriptive, even if this will make them longer. Particularly for functions it is good to specify in the name what they do.

For example for a function that calculates an anomaly use calculate_anomaly() rather than calc(). This also reduce the chances of using a reserved word.

 NB If you're using an IDE to edit your code then you can easily auto complete the names  

Use consistent naming across the code

Try to be consistent in the way you name your variable, constants and functions. There are a few conventions out there among the most common:

  • lowercase_words_with_underscores,
  • CapitalisedWords (also known as CamelCase),
  • ALL_CAPITALS for constants values 
  • mixedCase

Whatever you choose try to be consistent, use the same conventions for the same type of objects.

Code structure

Indents

 Some languages like Python enforce indenting, but even where it is not necessary indenting your code can help outlining the code structure. Again try to be consistent either use tabs or spaces, some languages like python have a preference for spaces.

Comments

Comments are extremely useful to document what your code is doing. Again you do not need to comment every line, as that might actually made the code less redable. But it is a good practice to have:

  •  a block of comments at the start of the code listing author, license,a a date for the last update, what the code does and how to use it.
  • similarly have a fe wlines of comments for each function or before a coherent block of code in the main program, for example before an "if/else" block.

It can also be useful starting a code by writing what do you want to do as comments. For example   # Assign arguments # Open data files # Calculate ... # Plot ... # Save output to file

 In this way you have a draft of your comments and you can work out the best structure, individuate blocks that can be included ina. function etc, before you even start coding. It can save you a lot of time.

Subdive your code using functions or sub-modules

Ideally a function should execute one coherent operation. As none of us it's a software developer we are not suggesting every line of code is a function , more than a logical block of lines should be included in a function. This is particularly true and useful if it's a block of code you might want to repeat in other parts of this same or others programs. Another good reason to enclose a block of code in a function it is to make it easier to add a test.   Use tests   It is a good idea to test at least critical parts of your code. You want to be sure that a calculation which is critical to your results, is producing consistent and correct results, no matter what changes you introduce to the same function or other part of your code. No matter how many tests you are conducting it is hard to preview all the possible ways a code can be used and it is often the case that as soon as you sue a different set of data you are going to find some bugs. Every time you fix a bug make sure you are adding a test to capture it. So you will know if accidentally you re-introduce it later on.

DRY code

One statement per line

Cramming a lot of instrcutions in one line of code won't make your code faster, just less readable. It will also make it more difficult to pinpoint what is causing an error if you have a few instructions in the same line.

Keep your files a reasonable length

Main message here is to be consistent and descriptive, in the end any conventions aim is to have consistency. Even if you are not using an established convention, being at least consistent across all of your codes will help making them more readable and re-usable.

Functions

Try to have only one exit point in a function

Return example

Style guides

 

References

This page was inspired by the seminar "Reproducible research how to write code that is built to last organised by DataTas. A recording is available on their facebook page.