Simple macros to define Proxy types for dicts arrays and others
Author jolin-io
2 Stars
Updated Last
1 Year Ago
Started In
July 2020


Build Status Coverage

Install it like

using Pkg
pkg"add ProxyInterfaces"

Load it like

using ProxyInterfaces

It gives you access to macros which define standard interfaces for your custom proxy type. Currently, the following interfaces are supported:

In addition it also exports the famous @forward MyWrapper.myfield func1, func2, func3 helper, for quick method forwarding to a struct field.


Let's take an example proxy type. A proxy type is understood as a type which wraps another type.

struct DictProxy{K, V}
  dict::Dict{K, V}

In this case it only wraps the standard dict with an additional Tag, namely the Type DictProxy itself.

You can now define standard dict functionality for your proxy with the following three lines

ProxyInterfaces.dict(::Type{DictProxy{K,V}}) where {K, V} = Dict{K, V}
ProxyInterfaces.dict(p::DictProxy) = p.dict
ProxyInterfaces.@dict DictProxy

With this you can now use standard dict syntax for your DictProxy

d = DictProxy(Dict(:a => 1, :b => c))
d[:a]  # 1
keys(d) # [:a, :b]
values(d) # [1, 2]
haskey(d, :b) # true
# d[:c] = 5  # WONT'T WORK because this is the immutable interface. use `ProxyInterfaces.dict_mutable` and it will work

Only these three steps are needed for every ProxyInterfaces respectivename:

  • overwrite ProxyInterfaces.respectivename(::Type{YourProxyType}) to define how the proxy TYPE maps to the original type
  • overwrite ProxyInterfaces.respectivename(p::YourProxyType) to extract the underlying original out of the given proxy instance
  • call ProxyInterfaces.@respectivename


Help is highly appreciated. There are many interfaces in Julia which are defined by documentation rather than code. This package ProxyInterfaces can work as a code reference.

In case you are missing a standard interface or a concrete function for an already supported interface, please open an issue. Pull request are also highly welcome.

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