Lazy parsing: Make findable in docs and use in openpmd-ls

docs/source/backends/adios2.rst

@@ -25,7 +25,7 @@ In order to activate steps, it is imperative to use the :ref:`Streaming API <usa
 
 ADIOS2 release 2.6.0 contained a bug (fixed in ADIOS 2.7.0, see `PR #2348 <https://github.com/ornladios/ADIOS2/pull/2348>`_) that disallows random-accessing steps in file-based engines.
 With this ADIOS2 release, files written with steps may only be read using the streaming API.
-In order to keep compatibility with older codes reading ADIOS2 files, step-based processing must currently be opted in to via use of the :ref:`JSON parameter<backendconfig>` ``adios2.engine.usesteps = true`` when using a file-based engine such as BP3 or BP4.
+In order to keep compatibility with older codes reading ADIOS2 files, step-based processing must currently be opted in to via use of the :ref:`JSON parameter<backendconfig>` ``adios2.engine.usesteps = true`` when using a file-based engine such as BP3 or BP4 (usesteps).
 
 Upon reading a file, the ADIOS2 backend will automatically recognize whether it has been written with or without steps, ignoring the JSON option mentioned above.
 Steps are mandatory for streaming-based engines and trying to switch them off will result in a runtime error.

docs/source/details/backendconfig.rst

@@ -36,7 +36,7 @@ For a consistent user interface, backends shall follow the following rules:
 Backend-independent JSON configuration
 --------------------------------------
 
-The key ``defer_iteration_parsing`` can be used to optimize the process of opening an openPMD Series.
+The key ``defer_iteration_parsing`` can be used to optimize the process of opening an openPMD Series (deferred/lazy parsing).
 By default, a Series is parsed eagerly, i.e. opening a Series implies reading all available iterations.
 Especially when a Series has many iterations, this can be a costly operation and users may wish to defer parsing of iterations to a later point adding ``{"defer_iteration_parsing": true}`` to their JSON configuration.
 
@@ -71,7 +71,7 @@ Explanation of the single keys:
   Please refer to the `official ADIOS2 documentation <https://adios2.readthedocs.io/en/latest/engines/engines.html>`_ for a list of available engines.
 * ``adios2.engine.parameters``: An associative array of string-formatted engine parameters, passed directly through to ``adios2::IO::SetParameters``.
   Please refer to the official ADIOS2 documentation for the allowable engine parameters.
-* ``adios2.engine.usesteps``: Described more closely in the documentation for the :ref:`ADIOS2 backend<backends-adios2>`.
+* ``adios2.engine.usesteps``: Described more closely in the documentation for the :ref:`ADIOS2 backend<backends-adios2>` (usesteps).
 * ``adios2.dataset.operators``: This key contains a list of ADIOS2 `operators <https://adios2.readthedocs.io/en/latest/components/components.html#operator>`_, used to enable compression or dataset transformations.
   Each object in the list has two keys:
 

include/openPMD/cli/ls.hpp

@@ -98,7 +98,8 @@ namespace ls
         try {
             auto s = Series(
                 argv[1],
-                Access::READ_ONLY
+                Access::READ_ONLY,
+                R"({"defer_iteration_parsing": true})"
             );
 
             helper::listSeries(s, true, std::cout);