Question about dest input to unsafe_gdalbuildvrt

[alex-s-gardner]

When supplying dest kwarg to ArchGDAL.unsafe_gdalbuildvrt i would expect the .vrt file to be written to dest but this is not the case. Is this the expected behavior?

using ArchGDAL
in_tifs = vector list of tif files
vrt_sep = ArchGDAL.unsafe_gdalbuildvrt(in_tifs, []; dest = "/path/to/file.vrt")
isfile( "/path/to/file.vrt") is false

[visr]

Can you try ArchGDAL.gdalbuildvrt? See also #142. It could be that the file is only written to disk when the finalizer gets called.

[alex-s-gardner]

I'm a little unclear on how to use gdalbuildvrt as the first input needs to be a Function

gdalbuildvrt(::Function, ::Any...; kwargs...)

[visr]

That is the signature of the do block syntax, like in https://docs.julialang.org/en/v1/manual/functions/#Do-Block-Syntax-for-Function-Arguments.

But I believe the same arguments as you used for the unsafe version are also supported. It just doesn't appear in the docstring.

[alex-s-gardner]

unfortunately 'gdalbuildvrt' does not accept the same inputs as unsafe_gdalbuildvrt

MethodError: no method matching gdalbuildvrt(::Vector{String}, ::Vector{Any}; dest="/mnt/devon-r2/shared_data/arcticdem/mosaics/v3.0/10m/arcticdem_v3.0_10m.vrt")
Closest candidates are:
  gdalbuildvrt(::Function, ::Any...; kwargs...) at ~/.julia/packages/ArchGDAL/AZONk/src/context.jl:264

[visr]

Ah you're right there is a difference between the two.
Note that it does not take a vector of paths, but a vector of opened datasets.
Here are two examples:

ds = ArchGDAL.read("LC08_L2SP_196026_20180101_20200902_02_T1_SR_B2.TIF")
vrt = ArchGDAL.unsafe_gdalbuildvrt([ds]; dest="a.vrt")
ArchGDAL.destroy(vrt)

And using do-blocks to directly clean up:

ArchGDAL.read("LC08_L2SP_196026_20180101_20200902_02_T1_SR_B2.TIF") do ds
    ArchGDAL.gdalbuildvrt([ds]; dest="b.vrt") do vrt
        # do something with vrt dataset if needed
    end
end

In the first example, the VRT is only written on the call to destroy.

[alex-s-gardner]

I previously had

in_tifs_str = ["data1.tif", "data2.tif","data3.tif","data4.tif"]
in_tifs = ArchGDAL.read.(in_tifs_str)
vrt_sep = ArchGDAL.unsafe_gdalbuildvrt(in_tifs, []; dest = out_vrt)
ArchGDAL.write(vrt_sep, out_vrt)

and ArchGDAL.write(vrt_sep, out_vrt) should be replaced with ArchGDAL.destroy(vrt)

To get the same functionality with gdalbuildvrt i need:

ArchGDAL.gdalbuildvrt(in_tifs; dest="b.vrt") do vrt
    ArchGDAL.write(vrt,out_vrt)
end

Is that right? If so it seems a bit counterintuitive to have to wrap this in a do block

[alex-s-gardner]

I guess this is related issue #164 that was partially resolved by allowing gdalbuildvrt to accept multiple datasets but the do block requirement persists.

looking at Working with Files it seems that gdalbuildvrt should also be callable without the do block

[visr]

gdalbuildvrt should also be callable without the do block

Yeah I think so as well. Let's keep this issue open to track that.

[yeesian]

If so it seems a bit counterintuitive to have to wrap this in a do block

Yeah it is, thank you for filing and explaining!