require "sketchup.rb"

module RefreshComponent
  def self.force_reload_component_definition!(model, definition)
    definition_path = definition.path
    definition_name = definition.name
    definition.name = definition.name + rand.to_s
##    definition.entities.add_cpoint(ORIGIN)     ## <== this causes GUIDs to match (fail)
    definition.save_as("/dev/null")              ## <== this causes new definition load (success)
    reloaded_definition = model.definitions.load(definition_path)
    puts "Old GUID; " + definition.guid
    puts "New GUID; " + reloaded_definition.guid
    reloaded_definition
  end

  def self.reconnect_component_instances!(model, old_definition, new_definition)
    model.start_operation("Remap instances")
    old_definition.instances.each { |instance| instance.definition = new_definition }
    model.commit_operation
  end

  def self.delete_component_definition!(model, definition)
    model.start_operation("Delete Definition")
    definition.entities.erase_entities(definition.entities.to_a)
    model.commit_operation
  end

  def self.refresh_component(model, definition)
    model.start_operation("Reload current component definition", true)
    reloaded_definition = force_reload_component_definition!(model, definition)
    reconnect_component_instances!(model, definition, reloaded_definition)
    delete_component_definition!(model, definition)
    model.commit_operation
  end

  def self.start
    model = Sketchup.active_model
    model.start_operation("Reload component definitions from file", true)
    model
      .selection
      .select { |entity| entity.is_a?(Sketchup;;ComponentInstance) }
      .map { |instance| instance.definition }
      .uniq
      .each { |definition| refresh_component(model, definition) }
    model.commit_operation
  end
end 

unless file_loaded?("refresh_component.rb")
    UI.add_context_menu_handler do |context_menu|
      context_menu.add_item("Reload Current Component Definition") {
        RefreshComponent.start
      }
    end
   file_loaded("refresh_component.rb")
end

This should then mean that a re-load of the original definition from the external SKP makes a new definition, auto-reusing its earlier name.

Next you need to swap out any existing instances of the original definition, to use the new definition...
definition.instances.each{|i|i.definition=new_definition}

Finally you can clear the entities of the original definition to remove it from the model's definitions list.
definition.entities.clear!
Note that you need to have all of this code inside a model.start_...commit_operation block for it to take immediate effect...

    model = Sketchup.active_model
    selection_set = model.selection
    selection = selection_set[0]
    definition = selection.definition
    definition.entities.add_cpoint(ORIGIN)   # not sure if I'm applying this to the correct entity
    new_definition = model.definitions.load(definition.path)
    puts "Old GUID; " + definition.guid
    puts "New GUID; " + new_definition.guid

I'm not sure if I'm applying add_cpoint() to the right entity; also I'm not sure whether creating an empty group is a better workaround as suggested in the thread, or how to do that!).

Finally, this is how I hope to replace the instances (based on someone else's example):

      definition.instances.each { |instance|
        instance.parent.entities.add_instance(new_definition, instance.transformation)
        instance.erase!
      }

Many thanks, and hugely appreciated!

Mike

Hmm, if you add an empty Group instead of a CPoint it also works; and then you may need to worry less about cleaning up since the empty group will get swept away.

Good point. (No pun intended)

I'll file up the issue internally so we'll look into it.

Have you tried to "touch" the old definition first by making a small change like entities.add_cpoint(ORIGIN) then trying to load the new?

Yes, I did! And it works. Happy camper.

Which is worse: CPU time or Disk I/O time?

You will need to do your own testing, but here's another possible work-around..

in Windows, save the definition as "nul" (or "\\Device\\Null"), and Mac as "/dev/null/"

These are special files that will not actually write to disk, but just throw away the data. But the definition path will be changed.

It's not exactly what you are asking for, but maybe better than creating double files on disk.

Thank you for your suggestion, Jim. I have made the test as you suggested:

definition = Sketchup.active_model.entities[0].definition

n = 50
Benchmark.bm do |x|
  x.report("save to nul ") { for i in 1..n; definition.save_as("/dev/null"); end }
  x.report("save to desk") { for i in 1..n; definition.save_as("/Volumes/.../Desktop/cubes.skp"); end }
end

                    user     system      total        real
save to /dev/null   7.770000   0.440000   8.210000 (  8.380249)
save to desktop     8.180000   0.630000   8.810000 ( 10.576788)

There is a marginal improvement. I imagine it would be a greater improvement if the save_as path was a network drive, so well worth noting.

Another lesson I learned in the process was understanding how fast the save_as method was. The component in the benchmark above was 3MB when saved. This works out at 0.055 seconds/MB on my Mac Pro (2008).

This contrasts markedly from the Definitions.load method, which guzzles a lot of CPU (it takes 6 times longer):

model = Sketchup.active_model

n = 50
Benchmark.bm do |x|
  x.report("load/save") {
    for i in 1..n
      definition = model.definitions.load("/Volumes/Storage/Users/Tommy/Desktop/Component.skp")
      definition.save_as("/dev/null")
    end
  }
  x.report("save to null ") { for i in 1..n; Sketchup.active_model.entities[0].definition.save_as("/dev/null"); end }
end
               user     system      total        real
load/save      59.010000   2.180000  61.190000 ( 61.211738)
save to null   8.720000   0.440000   9.160000 (  9.310672)

So the way ahead is clear. Save to change the path, then load only once.

You will need to do your own testing, but here's another possible work-around..

in Windows, save the definition as "nul" (or "\\Device\\Null"), and Mac as "/dev/null/"

These are special files that will not actually write to disk, but just throw away the data. But the definition path will be changed.

It's not exactly what you are asking for, but maybe better than creating double files on disk.

How about this alternative...
definition1.name >>> 'A' definition1.name = definitions.unique_name(definition1.name) ### e.g. A#1

Now RE-load the component SKP ['A.skp'] and there is nothing in its way.
Let's assume it's referenced as ' defintion2'.
It should arrive named 'A'.

Unfortunately, the component doesn't arrive named 'A'. definitions.load path returns the existing definition if the path is identical.

I have tried this:

` model = Sketchup.active_model

We have a single component in the model

old_definition = model.entities[0].definition
puts old_definition.path #=> '/HD/Users/User/cylinder.skp'

Rename the component

old_definition.name = model.definitions.unique_name(old_definition.name)

Attempt to reload the component

new_definition = model.definitions.load '/HD/Users/User/cylinder.skp'

if new_definition == old_definition
puts "The definitions are the same! This shouldn't happen, no?" #=> ...but it does
end`

It appears that the problem is not the clash of definition names when a definition is loaded, but the clash of paths between the new and old components. And you just can't change a definition path other than by loading it! Quite an omission in the API methinks.

In the meantime, my only other option is to temporarily rename the skp file from which the component is loaded using File.rename. It's messy, but it should work ok.

BTW - I am on Mac, Sketchup Pro 2015, and I experience this issue. I would be interested if this is the case on other platforms.

Now RE-load the component SKP ['A.skp'] and there is nothing in its way.
Let's assume it's referenced as ' defintion2'.
It should arrive named 'A'.

Now swap over definition1.instances.each{|i| i.definition = definition2 }

Next definition1.entities.clear!

If this whole operation is enclosed in a model.start_operation... model.commit_operation that now unused [an empty] ' definition1' [temporarily named as A#1] is automatically removed from the definitions-list...

Do a save_as on the current-component into a random-number-named SKP file in the user's Temp folder.
It's stored path in the original model's definitions is then changed.
Reload the externally changed component from its 'usual' external fixed-path, now it should overwrite in the model...
Delete the randomly number-named SKP file in the user's Temp folder, using File.delete(full_path)...

I did think of this workaround as a worst case scenario. It troubles me because of the (wasted) CPU time required to write the new file. I have potentially tens of MB of Skp files I need to load at a time. If I have to save an equivalent size of file every time, then, it potentially doubles the amount of CPU time.

Another option is to rename the file to be loaded first, then change it back after the load, although in this case, the path the newly loaded component points to would then be wrong.

We could really do with a new API function I think: ComponentDefinition.path=

Any other suggestions would be welcome!