Add convenience functions to set preferences (#88)

* add convenience functions to set preferences

* Fix typos

Co-authored-by: Hendrik Ranocha <[email protected]>

---------

Co-authored-by: Hendrik Ranocha <[email protected]>

README.md

@@ -99,6 +99,15 @@ julia> set_preferences!(
            UUID("7d669430-f675-4ae7-b43e-fab78ec5a902"), # UUID of P4est.jl
            "libp4est" => "/path/to/your/libp4est.so", force = true)
 ```
+Alternatively, you can use the convenience function `set_library_p4est!` to set
+the path:
+
+```julia
+julia> using P4est
+
+julia> P4est.set_library_p4est!("/path/to/your/libp4est.so")
+[ Info: Please restart Julia and reload P4est.jl for the library changes to take effect
+```
 On Windows you also need to set the path to the local build of the shared library
 of [`libsc`](https://github.com/cburstedde/libsc/tree/master), which is a subpackage
 of `p4est`. On other systems, this is not necessary as the library is already linked
@@ -108,6 +117,13 @@ julia> set_preferences!(
            UUID("7d669430-f675-4ae7-b43e-fab78ec5a902"), # UUID of P4est.jl
            "libsc" => "/path/to/your/libsc.so", force = true)
 ```
+Again, for convenience you can also use
+```julia
+julia> P4est.set_library_sc!("/path/to/your/libsc.so")
+[ Info: Please restart Julia and reload P4est.jl for the library changes to take effect
+```
+To delete the preferences again, you can call `P4est.set_library_p4est!()` and
+`P4est.set_library_sc!()`, respectively.
 
 Note that you should restart your Julia session after changing the preferences.
 To sum up, follow these steps to use
@@ -131,15 +147,13 @@ installation of the underlying C libraries.
   ```
 - Set [P4est.jl](https://github.com/trixi-framework/P4est.jl) preferences.
   ```julia
-  julia> using Preferences, UUIDs
+  julia> using P4est
 
-  julia> set_preferences!(
-             UUID("7d669430-f675-4ae7-b43e-fab78ec5a902"), # UUID of P4est.jl
-             "libp4est" => "/path/to/your/libp4est.so", force = true)
+  julia> P4est.set_library_p4est!("/path/to/your/libp4est.so")
+  [ Info: Please restart Julia and reload P4est.jl for the library changes to take effect
 
-  julia> set_preferences!(
-             UUID("7d669430-f675-4ae7-b43e-fab78ec5a902"), # UUID of P4est.jl
-             "libsc" => "/path/to/your/libsc.so", force = true)
+  julia> P4est.set_library_sc!("/path/to/your/libsc.so")
+  [ Info: Please restart Julia and reload P4est.jl for the library changes to take effect
   ```
 - Restart the Julia REPL and load the packages.
   ```julia

src/P4est.jl

@@ -6,7 +6,8 @@ using Reexport: @reexport
 # We need to load the preference setting from here and not from `LibP4est.jl`
 # since `@load_preference` looks into the module it is running from. Thus, we
 # load all preferences here and access them from the `module LibP4est`.
-using Preferences: @load_preference
+using Preferences: @load_preference, set_preferences!, delete_preferences!
+using UUIDs: UUID
 const _PREFERENCE_LIBP4EST = @load_preference("libp4est", "P4est_jll")
 const _PREFERENCE_LIBSC = @load_preference("libsc", _PREFERENCE_LIBP4EST)
 
@@ -45,6 +46,45 @@ to check whether `p4est` has been initialized.
 """
 package_id() = unsafe_load(cglobal((:p4est_package_id, LibP4est.libp4est), Cint))
 
+const P4EST_UUID = UUID("7d669430-f675-4ae7-b43e-fab78ec5a902")
+
+"""
+    P4est.set_library_p4est!(path; force = true)
+
+Set the `path` to a system-provided `p4est` installation. Restart the Julia session
+after executing this function so that the changes take effect. Calling this
+function is necessary when you want to use a system-provided `p4est`
+installation.
+"""
+function set_library_p4est!(path = nothing; force = true)
+    if isnothing(path)
+        delete_preferences!(P4EST_UUID, "libp4est"; force = force)
+    else
+        isfile(path) || throw(ArgumentError("$path is not a file that exists."))
+        set_preferences!(P4EST_UUID, "libp4est" => path, force = force)
+    end
+    @info "Please restart Julia and reload P4est.jl for the library changes to take effect"
+end
+
+"""
+    P4est.set_library_sc!(path; force = true)
+
+Set the `path` to a system-provided `sc` installation. Restart the Julia session
+after executing this function so that the changes take effect. Calling this
+function is necessary, when you want to use a system-provided `p4est`
+installation on Windows or when you want to use another `sc`
+installation than the one that `libp4est.so` already links to.
+"""
+function set_library_sc!(path = nothing; force = true)
+    if isnothing(path)
+        delete_preferences!(P4EST_UUID, "libsc"; force = force)
+    else
+        isfile(path) || throw(ArgumentError("$path is not a file that exists."))
+        set_preferences!(P4EST_UUID, "libsc" => path, force = force)
+    end
+    @info "Please restart Julia and reload P4est.jl for the library changes to take effect"
+end
+
 """
     P4est.init(log_handler, log_threshold)