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  • How does multiple implementing multiple COM interfaces work in C++?

    - by Martin
    I am trying to understand this example code regarding Browser Helper Objects. Inside, the author implements a single class which exposes multiple interfaces (IObjectWithSite, IDispatch). His QueryInterface function performs the following: if(riid == IID_IUnknown) *ppv = static_cast<BHO*>(this); else if(riid == IID_IObjectWithSite) *ppv = static_cast<IObjectWithSite*>(this); else if (riid == IID_IDispatch) *ppv = static_cast<IDispatch*>(this); I have learned that from a C perspective, interface pointers are just pointers to VTables. So I take it to mean that C++ is capable of returning the VTable of any implemented interface using static_cast. Does this mean that a class constructed in this way has a bunch of VTables in memory (IObjectWithSite, IDispatch, etc)? What does C++ do with the name collisions on the different interfaces (they each have a QueryInterface, AddRef and Release function), can I implement different methods for each of these?

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  • ?????create or replace???PL/SQL??

    - by Liu Maclean(???)
    ????T.Askmaclean.com?????10gR2??????procedure,?????????create or replace ??????????????????,????Oracle???????????????????procedure? ??Maclean ??2?10gR2???????????PL/SQL?????: ??1: ??Flashback Query ????,?????????????flashback database,??????????create or replace???SQL??source$??????????undo data,????????????: SQL> select * from V$version; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production CORE 10.2.0.5.0 Production TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 1 from dual';   4  end;   5  / Procedure created. SQL> select * from dba_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 execute immediate 'select 1 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             4 end; SQL> select current_scn from v$database; CURRENT_SCN -----------     2660057 create or replace procedure maclean_proc as begin -- I am new procedure execute immediate 'select 2 from dual'; end; / Procedure created. SQL> select current_scn from v$database; CURRENT_SCN -----------     2660113 SQL> select * from dba_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 -- I am new procedure SYS        MACLEAN_PROC                   PROCEDURE             4 execute immediate 'select 2 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             5 end; SQL> create table old_source as select * from dba_source as of scn 2660057 where name='MACLEAN_PROC'; Table created. SQL> select * from old_source where name='MACLEAN_PROC'; OWNER      NAME                           TYPE               LINE TEXT ---------- ------------------------------ ------------ ---------- -------------------------------------------------- SYS        MACLEAN_PROC                   PROCEDURE             1 procedure maclean_proc as SYS        MACLEAN_PROC                   PROCEDURE             2 begin SYS        MACLEAN_PROC                   PROCEDURE             3 execute immediate 'select 1 from dual'; SYS        MACLEAN_PROC                   PROCEDURE             4 end; ?????????scn??flashback query????,????????as of timestamp??????????,????PL/SQL????????????????undo??????????,????????????replace/drop ??????PL/SQL??? ??2 ??logminer??replace/drop PL/SQL?????SQL???DELETE??,??logminer?UNDO SQL???PL/SQL?????? ????????????????archivelog????,??????????????? minimal supplemental logging,??????????Unsupported SQLREDO???: create or replace?? ?? procedure???????SQL??????, ??????procedure????????????????, source$??????????????: SQL> ALTER DATABASE ADD SUPPLEMENTAL LOG DATA; Database altered. SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 1 from dual';   4  end;   5  / Procedure created. SQL> SQL> oradebug setmypid; Statement processed. SQL> SQL> oradebug event 10046 trace name context forever,level 12; Statement processed. SQL> SQL> create or replace procedure maclean_proc as   2  begin   3  execute immediate 'select 2 from dual';   4  end;   5  / Procedure created. SQL> oradebug tracefile_name /s01/admin/G10R25/udump/g10r25_ora_4305.trc [oracle@vrh8 ~]$ egrep  "update|insert|delete|merge"  /s01/admin/G10R25/udump/g10r25_ora_4305.trc delete from procedureinfo$ where obj#=:1 delete from argument$ where obj#=:1 delete from procedurec$ where obj#=:1 delete from procedureplsql$ where obj#=:1 delete from procedurejava$ where obj#=:1 delete from vtable$ where obj#=:1 insert into procedureinfo$(obj#,procedure#,overload#,procedurename,properties,itypeobj#) values (:1,:2,:3,:4,:5,:6) insert into argument$( obj#,procedure$,procedure#,overload#,position#,sequence#,level#,argument,type#,default#,in_out,length,precision#,scale,radix,charsetid,charsetform,properties,type_owner,type_name,type_subname,type_linkname,pls_type) values (:1,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15,:16,:17,:18,:19,:20,:21,:22,:23) insert into procedureplsql$(obj#,procedure#,entrypoint#) values (:1,:2,:3) update procedure$ set audit$=:2,options=:3 where obj#=:1 delete from source$ where obj#=:1 insert into source$(obj#,line,source) values (:1,:2,:3) delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 update idl_sb4$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub1$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_char$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub2$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_char$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub2$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_sb4$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub1$ where obj#=:1 and part=:2 and version<>:3 delete from idl_char$ where obj#=:1 and part=:2 and version<>:3 delete from idl_ub2$ where obj#=:1 and part=:2 and version<>:3 delete from idl_sb4$ where obj#=:1 and part=:2 and version<>:3 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 update idl_sb4$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 update idl_ub1$ set piece#=:1 ,length=:2 , piece=:3 where obj#=:4 and part=:5 and piece#=:6 and version=:7 delete from idl_char$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from idl_ub2$ where obj#=:1 and part=:2 and (piece#<:3 or piece#>:4) and version=:5 delete from error$ where obj#=:1 delete from settings$ where obj# = :1 insert into settings$(obj#, param, value) values (:1, :2, :3) delete from warning_settings$ where obj# = :1 insert into warning_settings$(obj#, warning_num, global_mod, property) values (:1, :2, :3, :4) delete from dependency$ where d_obj#=:1 delete from access$ where d_obj#=:1 insert into dependency$(d_obj#,d_timestamp,order#,p_obj#,p_timestamp, property, d_attrs)values (:1,:2,:3,:4,:5,:6, :7) insert into access$(d_obj#,order#,columns,types) values (:1,:2,:3,:4) update obj$ set obj#=:6,type#=:7,ctime=:8,mtime=:9,stime=:10,status=:11,dataobj#=:13,flags=:14,oid$=:15,spare1=:16, spare2=:17 where owner#=:1 and name=:2 and namespace=:3 and(remoteowner=:4 or remoteowner is null and :4 is null)and(linkname=:5 or linkname is null and :5 is null)and(subname=:12 or subname is null and :12 is null) ?drop procedure??????source$???PL/SQL?????: SQL> oradebug setmypid; Statement processed. SQL> oradebug event 10046 trace name context forever,level 12; Statement processed. SQL> drop procedure maclean_proc; Procedure dropped. SQL> oradebug tracefile_name /s01/admin/G10R25/udump/g10r25_ora_4331.trc delete from context$ where obj#=:1 delete from dir$ where obj#=:1 delete from type_misc$ where obj#=:1 delete from library$ where obj#=:1 delete from procedure$ where obj#=:1 delete from javaobj$ where obj#=:1 delete from operator$ where obj#=:1 delete from opbinding$ where obj#=:1 delete from opancillary$ where obj#=:1 delete from oparg$ where obj# = :1 delete from com$ where obj#=:1 delete from source$ where obj#=:1 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from idl_ub1$ where obj#=:1 and part=:2 delete from idl_char$ where obj#=:1 and part=:2 delete from idl_ub2$ where obj#=:1 and part=:2 delete from idl_sb4$ where obj#=:1 and part=:2 delete from ncomp_dll$ where obj#=:1 returning dllname into :2 delete from error$ where obj#=:1 delete from settings$ where obj# = :1 delete from procedureinfo$ where obj#=:1 delete from argument$ where obj#=:1 delete from procedurec$ where obj#=:1 delete from procedureplsql$ where obj#=:1 delete from procedurejava$ where obj#=:1 delete from vtable$ where obj#=:1 delete from dependency$ where d_obj#=:1 delete from access$ where d_obj#=:1 delete from objauth$ where obj#=:1 update obj$ set obj#=:6,type#=:7,ctime=:8,mtime=:9,stime=:10,status=:11,dataobj#=:13,flags=:14,oid$=:15,spare1=:16, spare2=:17 where owner#=:1 and name=:2 and namespace=:3 and(remoteowner=:4 or remoteowner is null and :4 is null)and(linkname=:5 or linkname is null and :5 is null)and(subname=:12 or subname is null and :12 is null) ??????????source$???redo: SQL> alter system switch logfile; System altered. SQL> select sequence#,name from v$archived_log where sequence#=(select max(sequence#) from v$archived_log);  SEQUENCE# ---------- NAME --------------------------------------------------------------------------------        242 /s01/flash_recovery_area/G10R25/archivelog/2012_05_21/o1_mf_1_242_7vnm13k6_.arc SQL> exec dbms_logmnr.add_logfile ('/s01/flash_recovery_area/G10R25/archivelog/2012_05_21/o1_mf_1_242_7vnm13k6_.arc',options => dbms_logmnr.new); PL/SQL procedure successfully completed. SQL> exec dbms_logmnr.start_logmnr(options => dbms_logmnr.dict_from_online_catalog); PL/SQL procedure successfully completed. SQL> select sql_redo,sql_undo from v$logmnr_contents where seg_name = 'SOURCE$' and operation='DELETE'; delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '1' and "SOURCE" = 'procedure maclean_proc as ' and ROWID = 'AAAABIAABAAALpyAAN'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','1','procedure maclean_proc as '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '2' and "SOURCE" = 'begin ' and ROWID = 'AAAABIAABAAALpyAAO'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','2','begin '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '3' and "SOURCE" = 'execute immediate ''select 1 from dual''; ' and ROWID = 'AAAABIAABAAALpyAAP'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','3','execute immediate ''select 1 from dual''; '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '4' and "SOURCE" = 'end;' and ROWID = 'AAAABIAABAAALpyAAQ'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','4','end;'); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '1' and "SOURCE" = 'procedure maclean_proc as ' and ROWID = 'AAAABIAABAAALpyAAJ'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','1','procedure maclean_proc as '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '2' and "SOURCE" = 'begin ' and ROWID = 'AAAABIAABAAALpyAAK'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','2','begin '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '3' and "SOURCE" = 'execute immediate ''select 2 from dual''; ' and ROWID = 'AAAABIAABAAALpyAAL'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','3','execute immediate ''select 2 from dual''; '); delete from "SYS"."SOURCE$" where "OBJ#" = '56059' and "LINE" = '4' and "SOURCE" = 'end;' and ROWID = 'AAAABIAABAAALpyAAM'; insert into "SYS"."SOURCE$"("OBJ#","LINE","SOURCE") values ('56059','4','end;'); ???? logminer???UNDO SQL???????source$????,?DELETE????????????,????SOURCE????????????PL/SQL???DDL???

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  • How can I create objects based on dump file memory in a WinDbg extension?

    - by pj4533
    I work on a large application, and frequently use WinDbg to diagnose issues based on a DMP file from a customer. I have written a few small extensions for WinDbg that have proved very useful for pulling bits of information out of DMP files. In my extension code I find myself dereferencing c++ class objects in the same way, over and over, by hand. For example: Address = GetExpression("somemodule!somesymbol"); ReadMemory(Address, &addressOfPtr, sizeof(addressOfPtr), &cb); // get the actual address ReadMemory(addressOfObj, &addressOfObj, sizeof(addressOfObj), &cb); ULONG offset; ULONG addressOfField; GetFieldOffset("somemodule!somesymbolclass", "somefield", &offset); ReadMemory(addressOfObj+offset, &addressOfField, sizeof(addressOfField), &cb); That works well, but as I have written more extensions, with greater functionality (and accessing more complicated objects in our applications DMP files), I have longed for a better solution. I have access to the source of our own application of course, so I figure there should be a way to copy an object out of a DMP file and use that memory to create an actual object in the debugger extension that I can call functions on (by linking in dlls from our application). This would save me the trouble of pulling things out of the DMP by hand. Is this even possible? I tried obvious things like creating a new object in the extension, then overwriting it with a big ReadMemory directly from the DMP file. This seemed to put the data in the right fields, but freaked out when I tried to call a function. I figure I am missing something...maybe c++ pulls some vtable funky-ness that I don't know about? My code looks similar to this: SomeClass* thisClass = SomeClass::New(); ReadMemory(addressOfObj, &(*thisClass), sizeof(*thisClass), &cb);

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  • Where in the standard is forwarding to a base class required in these situations?

    - by pgast
    Maybe even better is: Why does the standard require forwarding to a base class in these situations? (yeah yeah yeah - Why? - Because.) class B1 { public: virtual void f()=0; }; class B2 { public: virtual void f(){} }; class D : public B1,public B2{ }; class D2 : public B1,public B2{ public: using B2::f; }; class D3 : public B1,public B2{ public: void f(){ B2::f(); } }; D d; D2 d2; D3 d3; EDG gives: sourceFile.cpp sourceFile.cpp(24) : error C2259: 'D' : cannot instantiate abstract class due to following members: 'void B1::f(void)' : is abstract sourceFile.cpp(6) : see declaration of 'B1::f' sourceFile.cpp(25) : error C2259: 'D2' : cannot instantiate abstract class due to following members: 'void B1::f(void)' : is abstract sourceFile.cpp(6) : see declaration of 'B and similarly for the MS compiler. I might buy the first case,D. But in D2 - f is unambiguously defined by the using declaration, why is that not enough for the compiler to be required to fill out the vtable? Where in the standard is this situation defined?

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  • C++ Virtual Methods for Class-Specific Attributes or External Structure

    - by acanaday
    I have a set of classes which are all derived from a common base class. I want to use these classes polymorphically. The interface defines a set of getter methods whose return values are constant across a given derived class, but vary from one derived class to another. e.g.: enum AVal { A_VAL_ONE, A_VAL_TWO, A_VAL_THREE }; enum BVal { B_VAL_ONE, B_VAL_TWO, B_VAL_THREE }; class Base { //... virtual AVal getAVal() const = 0; virtual BVal getBVal() const = 0; //... }; class One : public Base { //... AVal getAVal() const { return A_VAL_ONE }; BVal getBVal() const { return B_VAL_ONE }; //... }; class Two : public Base { //... AVal getAVal() const { return A_VAL_TWO }; BVal getBVal() const { return B_VAL_TWO }; //... }; etc. Is this a common way of doing things? If performance is an important consideration, would I be better off pulling the attributes out into an external structure, e.g.: struct Vals { AVal a_val; VBal b_val; }; storing a Vals* in each instance, and rewriting Base as follows? class Base { //... public: AVal getAVal() const { return _vals->a_val; }; BVal getBVal() const { return _vals->b_val; }; //... private: Vals* _vals; }; Is the extra dereference essentially the same as the vtable lookup? What is the established idiom for this type of situation? Are both of these solutions dumb? Any insights are greatly appreciated

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