I hate repeating myself in shopify liquid, so to abide by the Don't repeat yourself (DRY) principle of software development, I created a spec for creating reusable functions in Shopify Liquid.

I've been using a technique for a little while now to create functions in shopify. With it's own sort of spec. I've been making them more and more, this repo will be dedicated to housing them.

Here's an example of a function that will check if a string (string) contains another string (query).

This would be in a file called function.string_contains.liquid.

{% assign return = false %}
{% if query %}
{% if string %}
  {% assign replaced = string | remove: query %}  
  {% if string != replaced %}
    {% assign return = true %}
  {% endif %}
{% endif %}
{% endif %}

Things to note:

• return is the return value of the function
• each argument started with pass_ (depricated?)
• return is assigned to false at the beginning of each funciton file
• the value of return changes somewhere in the funciton
• there is no support for returning multiple variables
• wrap the whole function in if statment per outside argument.
• up for debate should set any assigned variables to null at the end of a function {% assign replaced = null %?

{% assign query = '5"x7"' %}
{% assign string = 'hello world 5"x7"' %}
{% include "function.string_contains" %}
{% assign contains_query = return %}

Things to note:

• assign the arguments
• include the function file
• re-assign the return value