Do not use Base.get_extension

ext/RastersArchGDALExt/RastersArchGDALExt.jl

@@ -31,6 +31,8 @@ const DA = DiskArrays
 const GI = GeoInterface
 const LA = Lookups
 
+Rasters.is_loaded(::Rasters.ArchGDALExt) = true
+
 include("gdal_source.jl")
 include("resample.jl")
 include("warp.jl")

ext/RastersCoordinateTransformationsExt/RastersCoordinateTransformationsExt.jl

@@ -12,6 +12,8 @@ const RA = Rasters
 const DD = DimensionalData
 const LA = Lookups
 
+Rasters.is_loaded(::Rasters.CoordinateTransformationsExt) = true
+
 include("affineprojected.jl")
 
 end # module

ext/RastersGRIBDatasetsExt/RastersGRIBDatasetsExt.jl

@@ -10,6 +10,8 @@ const RA = Rasters
 const DA = DiskArrays
 const GDS = GRIBDatasets
 
+Rasters.is_loaded(::Rasters.GRIBDatasetsExt) = true
+
 include("gribdatasets_source.jl")
 
 end

ext/RastersMakieExt/RastersMakieExt.jl

@@ -6,6 +6,8 @@ using Rasters
 using Rasters.DimensionalData
 using Rasters.Dimensions
 
+Rasters.is_loaded(::Rasters.MakieExt) = true
+
 include("plotrecipes.jl")
 
 end

ext/RastersNCDatasetsExt/RastersNCDatasetsExt.jl

@@ -20,6 +20,8 @@ const RA = Rasters
 const DD = DimensionalData
 const LA = Lookups
 
+Rasters.is_loaded(::Rasters.NCDatasetsExt) = true
+
 include("ncdatasets_source.jl")
 
 end

ext/RastersProjExt/RastersProjExt.jl

@@ -28,6 +28,8 @@ const DA = DiskArrays
 const GI = GeoInterface
 const LA = Lookups
 
+Rasters.is_loaded(::Rasters.ProjExt) = true
+
 include("cellarea.jl")
 include("reproject.jl")
 end

ext/RastersRasterDataSourcesExt/RastersRasterDataSourcesExt.jl

@@ -8,6 +8,8 @@ using Rasters.Dimensions
 const RA = Rasters
 const RDS = RasterDataSources
 
+Rasters.is_loaded(::Rasters.RasterDataSourcesExt) = true
+
 include("constructors.jl")
 
 end # Module

ext/RastersStatsBaseExt/RastersStatsBaseExt.jl

@@ -8,6 +8,8 @@ const RA = Rasters
 import Rasters: _True, _False, _booltype, istrue
 import Rasters.DimensionalData as DD
 
+Rasters.is_loaded(::Rasters.StatsBaseExt) = true
+
 include("sample.jl")
 
 end # Module

ext/RastersZarrDatasetsExt/RastersZarrDatasetsExt.jl

@@ -8,6 +8,8 @@ using Rasters: Zarrsource
 
 const RA = Rasters
 
+Rasters.is_loaded(::Rasters.ZarrDatasetsExt) = true
+
 include("zarrdatasets_source.jl")
 
 end

src/extensions.jl

@@ -1,12 +1,31 @@
 # extensions
-function throw_extension_error(f::Function, package::String, extension::Symbol, args)
-    if isnothing(Base.get_extension(Rasters, extension))
-        throw(BackendException(package))
-    else
+abstract type Extension end
+
+# Concrete extension markers. These exist so callers can test availability
+# with `is_loaded(::Type{...})` instead of scattered `Base.get_extension` calls.
+struct ArchGDALExt <: Extension end
+struct CoordinateTransformationsExt <: Extension end
+struct GRIBDatasetsExt <: Extension end
+struct MakieExt <: Extension end
+struct NCDatasetsExt <: Extension end
+struct ProjExt <: Extension end
+struct RasterDataSourcesExt <: Extension end
+struct StatsBaseExt <: Extension end
+struct ZarrDatasetsExt <: Extension end
+
+# defaults to false
+is_loaded(::Extension) = false
+
+function throw_extension_error(f::Function, extension::Extension, args)
+    if is_loaded(extension)
         throw(MethodError(f, args))
+    else
+        throw(BackendException(extension))
     end
 end
 
+BackendException(e::E) where E <: Extension = 
+    BackendException(replace(string(nameof(E)), r"Ext$" => ""))
 
 # stubs that need ArchGDAL
 
@@ -90,7 +109,7 @@ savefig(b, "build/resample_example_after.png"); nothing
 
 $EXPERIMENTAL
 """
-resample(args...; kw...) = throw_extension_error(resample, "ArchGDAL", :RastersArchGDALExt, args)
+resample(args...; kw...) = throw_extension_error(resample, ArchGDALExt(), args)
 
 """
     warp(A::AbstractRaster, flags::Dict; kw...)
@@ -154,7 +173,7 @@ In practise, prefer [`resample`](@ref) for this. But `warp` may be more flexible
 
 $EXPERIMENTAL
 """
-warp(args...; kw...) = throw_extension_error(warp, "ArchGDAL", :RastersArchGDALExt, args)
+warp(args...; kw...) = throw_extension_error(warp, ArchGDALExt(), args)
 
 # stubs that need Proj
 
@@ -218,7 +237,7 @@ function cellarea(method::GeometryOpsCore.Spherical, dims::Tuple{<:XDim, <:YDim}
     return Raster(areas; dims)
 end
 
-_spherical_cellarea(args...; kw...) = throw_extension_error(_spherical_cellarea, "Proj", :RastersProjExt, args)
+_spherical_cellarea(args...; kw...) = throw_extension_error(_spherical_cellarea, ProjExt(), args)
 
 function _planar_cellarea(dims::Tuple{<:XDim, <:YDim})
     xbnds, ybnds = DD.intervalbounds(dims)
@@ -273,7 +292,7 @@ Rasters.sample(myraster, 5; weights=cellarea(myraster))
  @NamedTuple{geometry::Tuple{Float64, Float64}, ::Union{Missing, Float64}}(((110.0, 10.0), 0.5291143028176258))
 ```
 """
-sample(args...; kw...) = throw_extension_error(sample, "StatsBase", :RastersStatsBaseExt, args)
+sample(args...; kw...) = throw_extension_error(sample, StatsBaseExt, args)
 
 
 

src/methods/reproject.jl

@@ -72,7 +72,7 @@ function _reproject(source::GeoFormat, target::GeoFormat, dim::Union{XDim,YDim},
     reshape(_reproject(source, target, dim, vec(vals)), size(vals))
 end
 function _reproject(source::GeoFormat, target::GeoFormat, dim::Union{XDim,YDim}, vals::AbstractVector) 
-    throw_extension_error(reproject, "Proj", :RastersProjExt, (source, target, dim, vals))
+    throw_extension_error(reproject, ProjExt(), (source, target, dim, vals))
 end
 
 # Guess the step for arrays