## +24 ## Limitations and Problems in std::function and Similar Mitigations and Alternatives ## AMANDEEP CHAWLA ## Limitations and Problems in std::function and similar constructs Amandeep Chawla |

Deterministic C++ Exceptions for Embedded Systems • I expect a major change in this mechanism or alternatives in the near future. ## OUTLINE • Part 0: Prologue: What are Exceptions? • Part I: History and and Domain • Part II: Exceptions Overhead • Part III: Design Overview • Part IV: Alternatives • Part V: What's Next? ## DISCLAIMERS • This is not a talk about “Best practices of exceptions usage” language. ## PART I: HISTORY Let's go back a few years, to the era of C. There were two main alternatives: 1. Error codes (Return value) // do something, failure returns != 0 // do something foo related

apacheconfig - 設定 Apache (httpd) cvsconfig - 設定 CVS sndconfig - 設定音效系統 ... update-alternatives - 設定預設的指令，e.g.，vim as vi update-rc.d - System-V init script management update-menus - Debian information. #### 3.5.3 Alternative 指令 如果想用 vi 來執行 vim，請用 update-alternatives： # update-alternatives --display vi ... # update-alternatives --config vi Selection Command 1 /usr/bin/elvis-tiny 2 /usr/bin/vim default $$ * $$ , or type selection number: 2 在 Debian alternatives 系统中的項目都以符號連結的方式放在 /etc/alternatives/。 想設定你喜歡的 X 視窗環境的話，請用 update-alternatives 來修改 /usr/bin /x-session-manager 和 /usr/bin/x-window-manager。

c5bcc659b52c457ba0296861a31/p12_1.jpg) # WHAT ARE MY ALTERNATIVES? How React Native and NativeScript Change Your Mobile Strategy ## ALTERNATIVES HYBRID How React Native and NativeScript Change Your /p15_1.jpg)  ALTERNATIVES # JAVASCRIPT NATIVE How to Read and Write a Native Script (Change Your Mobile Strategy) Progress EXECUTION AT RUNTIME  ALTERNATIVES # CROSSCOMPILE React Native and NativeScript Change your Mobile Strategy ## POPULAR FRAMEWORKS

applications • We can’t easily change the transport mechanism • We can’t easily experiment with alternatives • Separate reading and writing of a message from the transport mechanism • I describe a library fixed sized arrays • The user has a choice: Both alternatives carry costs • Initialization vs. assignment • Std::string vs. C-style strings • Alternatives (averages over multiple runs, 12 strings, 189 and error-prone • Leave it to specialized support libraries, compilers, and generators • Many alternatives can be supported through code generation • Generated code is more likely to be correct than hand-written

/usr/bin/javac| |root@debian:/usr/local/java/# update-alternatives --install /usr/bin/java java /opt/jdk/jdkxxx/bin/java 100| |root@debian:/usr/local/java/# update-alternatives --install /usr/bin/javac javac /opt/jdk/jdkxxx/bin/javac both java and javac. This configuration can be made with| |root@debian:/usr/local/java/# update-alternatives --config java| |And then by typing in the Selection Number of the path /usr/local/java/jdkxxx/bin/java /bin/java. The same is made for javac| |root@debian:/usr/local/java/# update-alternatives --config javac| |To verify that from now on the Java SE from Oracle is used, you can check the version of java

enough, we need guarantees • We can (and do) use static analyzers but we need standards ## • Alternatives: We can 1. Change C++ 2. Start using another language 3. Enforce a variety of guidelines: Profiles mixing C and C++ in arguments • Often ignoring C++’s strengths • Often ignoring the weaknesses of alternatives • Often the safety mentioned is just memory safety • Often the need for unsafe constructs is progress • dynarray – a vector where the size s fixed at construction • Constraints on UB Design Alternatives for Type-and-Resource Safe C++ P2687 Safety Profiles: Type-and-resource Safe programming in

comparison https://aurora-opensource.github.io/au/main/alternatives/ ## Full comparison https://aurora-opensource.github.io/au/main/alternatives/ ### 1. Can you get it? ||Boost|nholthaus|bernedom/SI|mp-units|Au| Version-stamped for full reproducibility| ## Full comparison https://aurora-opensource.github.io/au/main/alternatives/ ### 1. Can you get it? ||Boost|nholthaus|bernedom/SI|mp-units|Au| |---|---|---|---|---|---| Detailed troubleshooting guide| ## Full comparison https://aurora-opensource.github.io/au/main/alternatives/ ### 1. Can you get it? ||Boost|nholthaus|bernedom/SI|mp-units|Au| |---|---|---|---|---|---|

2.5.8 Debian package file names ..... 64 2.5.9 The dpkg command ..... 65 2.5.10 The update-alternatives command ..... 66 2.5.11 The dpkg-statoverride command ..... 66 2.5.12 The dpkg-divert command programs (e.g., reportbug(1)) can invoke it. You can change it by the following. $ sudo update-alternatives --config editor The choice "/usr/bin/vim.basic" over "/usr/bin/vim.tiny" is my conf|conf image script for debconf system| |/var/lib/dpkg/alternatives/package\_name|the alternative information used by the update-alternatives command| |/var/lib/dpkg/available|the availability information

d'un paquet Debian ..... 66 2.5.9 La commande dpkg ..... 67 2.5.10 La commande update-alternatives ..... 67 2.5.11 Commande dpkg-statoverride ..... 68 2.5.12 Commande dpkg-divert ..... 68 reportbug(1)) de pourvoir l'appeler. Vous pouvez le modifier par la commande qui suit : $ sudo update-alternatives --config editor Pour les débutants, je recommande de choisir « /usr/bin/vim.basic » plutôt que brutalement ces paquets hors synchronisation, vous devriez chercher toutes les solutions techniques alternatives plus sûres qui sont compatibles avec votre système Debian actuel : — installez de tels programmes