Hey, I get some errors due to the way you created the TDataFrame:
$ root_docker test.C
snapshot: Pulling from rootproject/root-ubuntu16
Digest: sha256:4b9b9f1e8b797e25e818387515d4ee04d415a22ed759762d900ba90ef7b046c5
Status: Image is up to date for rootproject/root-ubuntu16:snapshot
-----------------------------------------------------------------
| Welcome to ROOT 6.11/01 http://root.cern.ch |
| (c) 1995-2017, The ROOT Team |
| Built for linuxx8664gcc |
| From heads/master@v6-09-02-2888-ge50a42c, Oct 03 2017, 19:18:00 |
| Try '.help', '.demo', '.license', '.credits', '.quit'/'.q' |
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root [0]
Processing test.C...
In file included from input_line_9:1:
/cur/test.C:10:15: error: no matching constructor for initialization of 'ROOT::Experimental::TDataFrame'
TDataFrame d("tree", files);
^ ~~~~~~~~~~~~~
/root-build/build/include/ROOT/TDataFrame.hxx:43:4: note: candidate constructor not viable: no known conversion from 'const std::initializer_list<const char *>' to
'std::string_view' (aka 'std::experimental::__ROOT::basic_string_view<char, std::char_traits<char> >') for 2nd
argument
TDataFrame(std::string_view treeName, std::string_view filenameglob, const ColumnNames_t &defaultBranches = {});
^
/root-build/build/include/ROOT/TDataFrame.hxx:60:4: note: candidate constructor not viable: no known conversion from 'const std::initializer_list<const char *>' to
'::TDirectory *' for 2nd argument
TDataFrame(std::string_view treeName, ::TDirectory *dirPtr, const ColumnNames_t &defaultBranches = {});
^
/root-build/build/include/ROOT/TDataFrame.hxx:61:4: note: candidate constructor not viable: no known conversion from 'const char [5]' to 'TTree &' for 1st argument
TDataFrame(TTree &tree, const ColumnNames_t &defaultBranches = {});
^
/root-build/build/include/ROOT/TDataFrame.hxx:63:4: note: candidate constructor not viable: no known conversion from 'const char [5]' to 'std::unique_ptr<TDataSource>' (aka
'unique_ptr<ROOT::Experimental::TDF::TDataSource>') for 1st argument
TDataFrame(std::unique_ptr<TDataSource>, const ColumnNames_t &defaultBranches = {});
^
/root-build/build/include/ROOT/TDataFrame.hxx:68:14: note: candidate template ignored: disabled by 'enable_if' [with FILENAMESCOLL = std::initializer_list<const char *>]
TTraits::IsContainer<FILENAMESCOLL>::value && !std::is_same<FILENAMESCOLL, std::string>::value, i...
^
/root-build/build/include/ROOT/TDataFrame.hxx:62:4: note: candidate constructor not viable: requires single argument 'numEntries', but 2 arguments were provided
TDataFrame(ULong64_t numEntries);
^
/root-build/build/include/ROOT/TDataFrame.hxx:39:7: note: candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 2 were provided
class TDataFrame : public TDF::TInterface<TDFDetail::TLoopManager> {
^
/root-build/build/include/ROOT/TDataFrame.hxx:39:7: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 2 were provided